CH Precision is one of the few companies that has been willing to go this route. The reason why is clear: CH has long been committed to easy, inexpensive field upgradeability for all its products. This philosophy explains the company’s use of modular card-cage construction and user-swappable function boards.

But the strategy reaches its zenith when it comes to the DAC functions of the I1 integrated amp, D1.5 disc transport, and C1.2 digital controller. Here, the use of powerful DSP and FPGAs on the DAC card allows for virtually unlimited upgrades—even complete rewrites, theoretically—with zero hardware costs and zero hassle. Further, CH Precision offers the firmware updates for free.

Theory Meets Reality

Those of you who read my review of the Metronome DSC know that, to my chagrin, it sonically clobbered my own CH Precision I1. In the process, the Metronome won a Golden Ear Award and became my new reference DAC/streamer.

However, unbeknownst to me, the restless folks at CH Precision were already working on a significant upgrade to the DAC within the C1 digital controller, which they would soon transfer to the I1 and D1.5. Their goals were twofold: 1) dramatically improve sonic performance via a wholesale revision of the DAC code; and 2) implement full MQA support. CH has now released the new I1 firmware, dubbed version 2.2.

This update is most decidedly not a case of tinkering around the edges. Among other things, the DAC now uses fixed-point rather than floating-point arithmetic. (See “A Conversation with Mr. C and Mr. H of CH Precision” for details about what changed and why.) Full MQA support is now so thoroughly implemented that, just as there is an assignable front-panel display color for analog and digital sources, there’s now a new color for MQA sources.

I got a preview of the new firmware at the 2022 Munich show. There, a system featuring all-CH electronics and Rockport Lyra speakers—playing Red Book CDs, no less—won my Best Sound of the Show Award. However, I had no idea how much of that fabulously realistic sound was due to the Rockports, the 10-Series CH components (which now form the heart of Robert Harley’s reference system), or the DAC firmware. The only way to find out was to try the upgrade in my own system.

A/B comparisons are highly elucidating when you can go back and forth at will. However, in this scenario, once I upgraded the firmware from “A” to “B,” as it were, there’d be no going back to A. The next best thing would be to establish an independent reference point, “X,” to which both A (before update) and B (after update) could be compared. Handily enough, I had the ideal “X” in the Metronome DSC.

I began by revisiting the comparison between the Metronome and the pre-upgraded I1. Consistent with my original review, the differences were not subtle. The first track I played was one of those that had impressed me so much in Munich, “True Love Ways” from the Buddy Holly CD From the Masters. Compared to the DSC, the I1 sounded dynamically and spatially flat. Flat, too, were the images, which on the Metronome had a holographic quality. In addition, bass was comparatively meager through the I1, and the CH didn’t deliver the richness that makes this track so seductive.

Similarly, on my standard test track, Michael Wolff’s “The Conversation,” the I1 again sounded compressed, and timbres had a sameness up and down the piano keyboard and at different volumes. This was in stark contrast to the timbral variety and vivacity delivered by the Metronome.

Having confirmed my original impressions of the I1’s DAC, it was time for the firmware upgrade. I was anxious to discover whether the changes it wrought were subtle, as such firmware upgrades on other DACs tend to be, or on the scale promised by the I1’s architecture. The upgrade process itself was simple. I downloaded the new firmware from the CH website to my computer, copied it to a thumb drive, plugged the drive into the USB service port on the back of the I1, and selected Upgrade Firmware from the CH’s menu. Some moments of suspense followed as I waited for the process to complete. Then I listened.

What I heard was no minor change. In fact, if I hadn’t done the upgrade myself, I never would have believed I was listening to the same DAC card in the same I1. This was a completely new DAC with an entirely different—and much better—sound. The I1, previously anemic sounding, now manifested the richness of the Metronome. “The Conversation” was transformed, with mesmerizing timbral diversity, fleshed-out images, and dynamics that were everything you’d expect from a CH component. Bass in the I1 DAC had gone from a liability to a strength. Indeed, the two DACs now sounded far more similar than different. Both were stellar.

Over time, as I listened more deeply, I found a few more minor differences between the two units. The Metronome, as you might expect from its name, has marginally better timing resolution, and its uniquely quiet background gives it a smidge more dynamic range. On the other hand, the post-upgrade CH has the edge when it comes to top-end smoothness, and its bass is more powerful and better defined. Preference will come down to personal taste and even the type of music one favors.

Conclusion

By now it should be apparent that CH’s first major DAC firmware upgrade is an unqualified success. Sonically, this new DAC is not only much improved; it goes toe-to-toe with the best DAC I’ve had in my system. And it cost me nothing! All this is thanks to CH’s forward-thinking, upgrade-minded architecture. Anyone with a CH integrated amp, transport, or digital controller should, if he hasn’t done so already, immediately download the latest firmware. He’ll be shocked at the upgrade he just received for nothing, with no hardware change required either. I only wish all DACs could do that.    

Andy Quint’s BACCH Preview:  • Preview: Andrew Quint on BACCH-SP Ste…  

Guide to High-End Room Treatment:   • A Guide to High-End Room Construction…  

BACCH-ORC requires acoustic measurements with the BACCH-BM in-ear microphone and is therefore available only for the Audiophile Edition and above.

The BACCH-ORC module can be added to BACCH-dSP at any time for $1000. However, in appreciation of the trust and enthusiastic support of our existing customers, we are offering a free perpetual license for the BACCH-ORC module to all those who have purchased BACCH-dSP Audiophile (or a higher edition level) by March 3, 2024, and whose 1-year Tech Support and Version Update Service Plan has not expired by that date. If you are receiving this email message, and you have BACCH-dSP Audiophile, Audiophile+ or Pro, you qualify for this offer. The second stage of the installation process described below will automatically add the ORC module to your BACCH-dSP app. After installation, we advise you to download and read the latest Version Notes for BACCH-dSP 14 to learn the simple steps for making and applying ORC filter..

If you are receiving this message, and you have the Intro edition, you are entitled to the new version update to BACCH-dSP 14 Intro, and we advise you to follow the instructions below to download and install it. If you decide to upgrade to the Audiophile edition and above at any time in the future, we are happy to offer you a free perpetual license for BACCH-dSP.

Installing BACCH-dSP 14 with ORC is a two-stage process:

In Stage I, you follow the steps below to download and run the latest installer to install BACCH-dSP 14 on your Mac. You can then run BACCH-dSP 14 as usual at the edition level you have purchased but without ORC, which requires a separate upgrade license.

If you have the Audiophile edition or above, you can proceed to Stage II of the installation when you are ready to add the BACCH-ORC module.

In Stage II you follow the steps below to send us a request for the ORC upgrade activation. You will then receive an email message from Theoretica with simple instructions for activating the perpetual license for the BACCH-ORC module. Please note that once you send the request you will not be able to use BACCH-dSP if you quit it again, until you receive the ORC upgrade activation from us. This can take up to 12 hours in the worst case (although we often reply within the hour).

Please note that unlike recent BACCH-dSP updates, v14 is a major “deep update” and this installation will overwrite all your existing BACCH-dSP settings and previously and BACCH filters. Also, please note that due to the deep changes in v 14, you will not be able to import filters and settings exported with previous versions of BACCH-dSP. You will need to reload you BACCH-BM equalization file, reset all your settings (or run the appropriate auto-configure script), load your individual BACCH-BM equalization file, and remake your BACCH filters from scratch. As long as your service plan is valid, you can contact us at info@theoretica.us for assistance in this process.

BACCH-dSP 14 can run under the latest Mac OS, Sonoma 14.3.1 , as well as all previous Mas OS versions down to Mojave 10.13. Please do not update to a version of Mac OS past the present latest version (Sonoma 14.3.1), before you hear from us confirming that BACCH-dSP is compatible with that Mac OS.

BACCH processing previously has been done via a special box and software that is quite expensive. Andy Quint reviewed this system here a year or so ago. Recently, Theoretica released a version that runs on Apple Mac computers and gets the price point down from circa $20k to under $2k. There are various versions of BACCH4Mac, starting at $980 plus the cost of a Mac, assuming you don’t have an M2 Mac lying around unused. So, about $1600 for the most basic version. The fancier versions go up to about $8700 plus the Mac for the Pro setup, but you probably don’t need the recording capabilities or the headphone processing of maximum supreme BACCH4Mac, so figure $6700 plus the Mac. This is called the Audiophile version, which offers head movement tracking and custom compensation for the exact shape of your head.

We reviewed the BACCH4Mac Pro version, but it does exactly what the Audiophile version does when used in a stereo system. The software is somewhat complex to set up, but Theoretica does a call with you and runs your Mac remotely so that they are both showing you how to do setup and actually doing the setup. This takes perhaps an hour, and you are good to go. After that, you really don’t have to touch the software unless you change your stereo setup.

The BACCH4Mac was used in my reference system as follows:

• Ethernet from router to MacMini (M2)
• Roon Core running on MacMini
• Roon Core streaming Qobuz and Tidal to BACCH4Mac on the same MacMini
• Head-tracking camera connected via USB to MacMini
• Babyface Pro mic preamp enabling low-level software license used by BACCH4Mac
• MacMini output via USB to dCS Lina DAC (with Master Clock)
• dCS Lina output to Audio Research Ref 6 mk2 preamp
• Ref 6 to PS Audio BHK 600 mono amps
• BHK 600 amps to Magico A5 speakers

I ran other digital sources straight into the dCS DAC. Analog sources went straight to the Audio Research preamp. This allowed me to compare various signals to those going through BACCH4Mac without ever touching the MacMini or BACCH. BACCH4Mac can do A/D conversion if you want to use it with analog sources.

Okay, But What Problem Are We Trying To Solve Here?

We have said, and it bears repeating, that there are at least three great unsolved issues with stereo music reproduction in the home:

• The problem of bass in real rooms
• The problem of visual imagery
• The problem of spatial presentation

BACCH4Mac is built to address the latter of these. That is, some people, your humble reporter included, observe that the soundspace and instrument placement and rendering of instruments in conventional stereo is not fully realistic. A common problem is that performers seem to be paying from within the speakers at times. I also like Siegfried Linkwitz’ version of the problem, which is that small performers seem to be playing on a stage arrayed between the speakers. Audiophiles, myself included, work hard to make this stage as wide and as deep as is realistic, and then get performers placed on it correctly. Audio companies and recording engineers work hard to enable this, but generally within a framework that accepts these constrained stage limitations. BACCH asks “why is this limited soundspace happening in the first place and can we address it?”

Okay, fasten your seatbelts because this is the part of the presentation where we have to unseat some common assumptions. At least my experience was that some unseating is needed.

The first assumption that I find many audiophiles have is that stereo is designed to allow placement of performers anywhere between the speakers. That, often, is what we think stereo means. So, if a performer is on the left side of the stage, he or she would be presented from the left speaker. If the performer is in the middle of the stage, he or she would be presented in the middle. If the performer is center-right, he or she would be presented between the middle and the right speaker.

But if you go back to the original Blumlein patent for stereo from 1931, this wasn’t the idea. Or, said differently, this ‘between the speakers’ idea is wrong. Instead, stereo is intended to be able to present the performers where they were during the performance, unrestricted by speaker location.

To further understand what the idea was, you may have to give up another idea: many people think the speakers are delivering a version of the instrument sounds that were recorded and presenting them into the room in a simulation of what happened in the concert hall or the club. You then hear something that is roughly like what you would have heard live. The speakers set up a virtual performers and the reflections in the room create a sense of the space.

But this is not what happens, or at least what should happen. What actually happens is that the recording consists of two data streams, one for the left channel and one for the right channel. These data streams have all the information about performer placement encoded in them. That is, if a performer were to the left of the mics used for the left channel, the data about that leftward placement is on the recording. This data is sent to your ears from the speakers, and here’s the kicker: your ear and brain have the ability to decode the data and place the performer where he or she was when the recording was made. Which means that a performer who was to the left of the left mic can be placed so that you will perceive it being to the left of the left speaker.

Yup, your speakers are data conduits not performer simulators. Let that sink in for a minute.

Now, I still haven’t really explained where the problem lies. So, here we go. My apologies if your head hurts.

(It is important to note that the explanation below is a greatly simplified summary of how this works. As a simplification, it is intended to give you a feel for why normal stereo doesn’t work right and very roughly how it can be fixed. If you come away with that sense that there is an addressable problem, then I urge you to let the proof be in the pudding and attend to the sonic results of BACCH which I describe next. And listen for yourself. But, if you are the kind of person who wants to follow the logic in detail, step-by-step, this won’t get you there. There are 52 pieces of intellectual property in BACCH and Blumlein made 70 key points in his stereo patent and there is more that has been learned about stereo in between. I’ve reduced this to three steps and inevitably that doesn’t get you anything like all the detail to prove that BACCH makes sense. You’re either an empiricist at heart or you’re not, and if you’re not what follows won’t help.)

Let’s start with a live performance. To keep this as simple as possible, I’m going to concentrate on what happens to your left ear and to the left microphone. But, it is very important to say, the right ear and right mic are logically just like this. I’m also going to simplify by assuming just two performers and just two mics. The logic would be the same with more performers and hall reflections and more mics, but the algebra gets messy.

Okay, take a look at this diagram. What your left ear hears in a live performance is shown here. Your left ear hears the direct sound from the left performer. Your left ear also hears the sound from the right performer but modified by the distance and time delay and frequency shaping caused by your head. This is called the head-related transfer function, but I’ve simplified this by calling what the left ear hears from the right performer R(ModH) for “Right Modified by Head”.  I’ll come back to this, but ideally your stereo would present your left ear with L+R(ModH). You will soon see that it doesn’t.

Now, consider what happens when we make a recording of these two performers. Instead of your head, I’ve shown two mics in a Blumlein arrangement. The left mic, which will feed the left channel, records the direct sound from the left performer. It also records the sound from the right performer, modified by the distance and time delay and off-axis pickup pattern of the left mic. So, in my algebraic representation, the left channel of the recording is L+R(ModM) or left plus right modified by the mic. Now this isn’t exactly what your left ear heard, but it is similar in form.

Then consider what you hear on your stereo. Again, we will just consider what your left ear hears to keep it simple. From the left speaker, your left ear hears L+R(ModM). So far so good. That is pretty similar to the data stream your left ear heard in the concert hall, which is L+R(ModH). But, your left ear also hears sound from the right speaker, which is R+L(ModM). Now hang with me on thinking of these as data streams not virtual performers. When you think of it that way, you realize that with standard stereo we have a huge error term. Everything from the right speaker that your left ear hears shouldn’t be there! You are hearing R+L(ModM) in the left ear and you should not hear any of that term in the left ear in order for the left ear to hear something like what it would hear in the concert venue.

Now, to understand BACCH, I want you to consider that standard stereo presents a massive distortion signal to each ear. That distortion signal is R+L(ModM) for the left ear. Assuming that the right speaker signal at the left ear is roughly the same magnitude as the left speaker signal, standard stereo has something like 50% distortion. Woah! Now this isn’t a-musical distortion, it isn’t for example harmonic distortion or noise, so that number overplays how audibly distracting this error term is. But, the error term is big. And it is spatially distorting.

Getting back to BACCH processing, the BACCH software removes the error term. They call it crosstalk cancellation, but it isn’t the internal to equipment crosstalk that they’re talking about. It is basically an additive signal that is imposed by stereo reproduction that adds a second erroneous layer of music on top of what happened in the hall or club. This crosstalk removal is “all” BACCH does. So maybe the magnitude of the change is more understandable if I say BACCH processing removes a 50% distortion.

Now, removing this amount of error or distortion in practice without damaging the music along the way is no simple task. So, when I discuss the sound quality of BACCH I will address how well it does its work without extraneous damage. Stay tuned.

How Does BACCH Processing Sound?

BACCH makes a dramatic difference to the sound you hear. That difference varies from recording to recording.

The recording-to-recording observation brings up important point number 1. BACCH processing is not adding something to the signal in an attempt to simulate what you would have heard in the concert hall or club or recording studio. BACCH is subtracting a signal that shouldn’t be there to properly render the performers in space.

Let me give you some examples of how BACCH processing sounds.

With the Mozart string quintets, K515 and 516 with the Eben Quartet in high res, you first notice that the quintet is spread out in a very clear semi-circle, and the semi-circle extends very slightly beyond the width of the speakers. Then you notice that each instrument seems to stand out in space so it sounds like the players are actually occupying not just the semicircular positions that I described before but that each player seems to have an instrument that’s got a whole spatial property to itself.  As it would in real life if it were actually in your room resonating. In addition to the semicircular array of the instruments, the players on my reference system, particularly second violin and viola, seem to be behind the front wall. The stage depth with BACCH is deeper than just working in the space behind the speakers.

Next up I listened to The Freewheeling Bob Dylan from 1963 in high res. This is a really simple recording: it’s Bob, his guitar and his harmonica. With BACCH, you hear Bob in the center where you would kind of expect him if you think about how most stage performances are arranged, and then the recording engineers put his guitar on the right and the harmonica on the left. That isn’t how it would sound live, but this is a studio recording and you hear how the engineers placed things so that it sounds a bit like a trio. Apart from the deviation between studio and live, what’s impressive is the guitar occupies a space that extends outside of the right speaker and feels appropriately sized for the dreadnought Gibson guitar that Bob played in this period. This album does raise a persistent BACCH conundrum which is: do you want to hear musicians where the recording engineers placed them? You’ll have this issue in normal stereo of course, just not so clearly presented.

With the Esbjorn Svensson Trio, on the jazz album From Gagarin’s Point of View, the mix seems to me to be just about perfect with the performers arrayed on a stage in front of you with a real sense of depth. The tonality of the instruments is beautifully rendered, but the part that the BACCH processor adds if you will, is the sense that the players are playing in a large three-dimensional space. The reverb off the rear wall and the sidewalls and the front wall just seems so much more natural and like they were actually playing in a club, that it’s borderline transformative. The reason it feels transformative is that this added realism subconsciously helps you suspend disbelief. “Realism,” it turns out, isn’t an analytical, nerdy thing alone, it is a critical part of engaging with the music.

I tried the Mahler Symphony No. 1, this time with the Minnesota Orchestra. This is a Hi-Res recording made in 2019. Here I had a similar feeling that BACCH processing enhanced the sense of the orchestra being in a large three-dimensional space. instruments that are farther toward the back of the hall were presented properly, with horns and timpani appearing toward the back of the hall. The reverberant field is so well captured that the sense of the musical reflections floating above the orchestra is a little bit stronger than what I’m accustomed to with stereo, but it is very much like what you hear when you’re actually in the concert hall.

Now let’s talk about Pink Floyd’s Dark Side of the Moon. This is a recording where I’m pretty confident the band wanted a surround sound kind of effect rather a simulation of what it would be like to hear the band playing live on a stage 200 feet away from you. The famous first track with the heartbeat is called “Speak to Me”. Toward the end of the track there are some voices and helicopter effects and chimes, and these are placed way outside of the normal stereo stage area. In fact, these are located slightly behind the listener in some cases. I mean that you hear the sounds as if they were coming from a speaker set behind you and to the left or right. But there is no speaker there. As I said, the data is locating the sound there, and is not muddled via BACCH, so you hear it where the recording team presumably wanted it. The helicopter and voices also move around laterally in a clear way as if they were moving around your room.

Then we move onto the track “Breathe”, and the listener is placed in the center of the band. David Gilmour‘s guitar is to the left and slightly behind the listener. Richard Wright’s organ is to the right rear of the listener and Roger Waters and Nick Mason are presented on the traditional stereo stage in front of you. I do feel that the instruments move around a little bit and that again seems to have been intentional. It’s very much a surround sound, listener in the center of the band, psychedelic kind of thing.

Listening to Radiohead on the In Rainbows album, I was again struck by the ability of BACCH processing to take each instrument and give it its own place in the mix without blurring it together with other instruments. So, I can honestly say I haven’t heard this album sound as good on my reference system as it does with BACCH. Now we also need to consider that this appears to be an album where the engineering places some of the instruments outside of the normal stereo stage. I assume that’s what Radiohead wanted. You might find that slightly unnerving, although for this kind of music, it seems somehow appropriate. And it was very engaging. The approach is a little bit like the semi-psychedelic stuff from Pink Floyd, but the recorded effects were more subtly presented here than on Dark Side of the Moon.

I do want to describe an addressable downside of BACCH processing. On Art Blakey and the Jazz Messenger’s album Buhaina’s Delight, the players are arranged in a 270° arc around the listening position that may be effectively where the microphones were. However, I have to say it’s a little bit odd to hear Art Blakey playing in a position slightly behind where I’m sitting, and on the right side. There is a horn off my off my left side. The other players are arrayed as you would typically hear on stereo between the speakers. Not what you would hear in a club. This studio recording is from 1961 and I just don’t think stereo recording in the studio was evolved to the point where the engineers were trying to do this. I think the engineers wanted Blakey right front so they pan-potted him hard right and the data on the recording has this placed at the right rear. I got similar results with Dave Brubeck’s Time Out, from 1959. But Bill Frissell’s Valentine, a jazz trio studio recording from 2020, sounds phenomenal in the sense that the performers are where you would expect them.

You can set up BACCH processing with choices of different levels of crosstalk cancellation to address this issue. With 25% rather than 100% cancellation, the Art Blakey recording sounded more normal and I think correct.

The fact that recordings can present performers in a 360-degree arc with BACCH processing doesn’t mean that all recordings will be spread out in that arc. BACCH isn’t imposing a pre-determined “envelopment factor” on the recording. It that means that 360 degrees is the maximum placement freedom that the engineers can have in choosing where the recording places sound. If you’re on full crosstalk cancellation and the engineer has placed somebody far left and behind you, essentially -135° from dead center or +135° from dead center, you’ll hear them there. But if the engineer placed the musician in the middle between the speakers, as with the Bob Dylan recording, the performer is going to be in between the two speakers in the center just like you’re used to from time immemorial. So, with BACCH processing, the stage width will vary from recording to recording, and dramatically so.

Now there is a reasonable argument that the recording engineers probably didn’t listen with BACCH when mixing and mastering. So, they expected playback via normal, cross-talk laden stereo. So, BACCH represents a distortion of what they wanted if you assume they were able to get what they wanted. I will counter that with the observation that many modern recordings seem to be made in a way that manages to take studio work and live work and present it spatially in an okay rendition of space that become significantly more realistic with BACCH. That is, without BACCH, a good recording is rendered within the limits of normal stereo in a good spatial manner. But the techniques used to present the performers spatially on limited stereo systems seem to encode the performers in a way that has better data than you normally hear. Until you use BACCH.

An analogy may help. It is as if the engineers know that bass below 50hz is important. So, they develop techniques to get flat, accurate bass from 25-50hz, even though their studio monitors roll off below 50 hz. Then, when you play these recordings on a system flat to 25hz, it sounds great and natural. Listening on rolled-off monitors wouldn’t support this, so they develop rules to get around the limits of the system. The engineers are smart enough to make the recording accurate, even though their monitors don’t let them hear it.

I do think mixing and mastering with BACCH would be even better, of course. But I am suggesting that, in a lesser of two evils world, current recordings via BACCH often (>60% of the time) sound more spatially convincing than without BACCH.

All this talk about arcs and performer placement may do an injustice to one of the big benefits of BACCH. To help you imagine this other element, I would say BACCH seems to give each instrument not just its place on the stage, but it’s own sense of 3D air and size. It’s almost as if each instrument gets its own speaker and that speaker can devote all its energy to perfectly representing the sound of that one instrument. This idea that each instrument has its own channel gives you a sense of the purity and the clarity of harmonics and instrumental size and detail that BACCH delivers. This could be summarized as a sense of higher resolution. I want to keep emphasizing that this clarity or resolution isn’t spectral byproduct, it’s a spatial byproduct. You can better hear into what’s going on in the instrument.

And you get more suspension of disbelief. The more that the spatial qualities don’t appear locked into an artificial construct (e.g. the speakers or the tiny stage) the more you listen to music differently and, I thought, in a more engaged way. Some of this also comes from the music seeming to be played in a real, large space. The performers are on stage as you would expect, but they are playing in a concert venue that has walls left and right and behind you. Linkwitz’ tiny stage doesn’t do this, and you know it even if years of listening has made its absence seem normal.

I also need to comment in a broader way on spectral balance. Apparently one of the hard things (there are more than 50 pieces of intellectual property here) about crosstalk cancellation is doing it without disturbing the frequency response of the music. I won’t say that the balance of my reference system was the same with and without BACCH, but it was very close to the same. I never felt the need to describe the impact of BACCH processing in frequency response terms, even though that is the way changing components often shows up in my head.

Summary

I hope it is obvious that I think BACCH processing is a significant advance in stereo reproduction. On perhaps 80% of the albums you might play, especially from the last 40 years, BACCH4Mac delivers an image that is freed up from the confines of your speakers. This gets some parts of the image off the speakers and expands stage width, depth and height in an important way. That “important way” is to make the performers seem more spatially real and to help with the suspension of disbelief that often accompanies recorded music. Performers and instruments take on a more 3-dimensional quality and their freedom for spatial placement by the recording engineers gives a 3-dimensional feel to the stage. Additionally, BACCH helps to present the ambient cues from the recording venue so that you subconsciously feel you are in a real space.

Another analogy may be useful. Conventional stereo is a bit like watching performers on a television. As we improve the many core technologies of stereo, the TV gets bigger, and the resolution gets higher, and the colors are more accurate. But you never really escape the sense that the performers are locked inside a window defined by the edges of the TV, and you often sense that the image is actually flat, even though high-res helps generate a better sense of depth. With BACCH, continuing the analogy, it is like watching movies on a hologram generator or a VR headset (without needing a headset). There isn’t a hard edge to the stage, depth is more realistic, and you feel like you are in the room with the actors who themselves are three-dimensional.

Now, recordings have been made and could continue to be made that are more in the surround-sound vein. BACCH4Mac does an impressive job with these, but I do think such recordings are musically unusual and it is important to understand that this extreme capability for placing performers is not what BACCH processing is primarily about. I want to add that I suspect that if BACCH4Mac couldn’t do accurate surround sound, it couldn’t reveal the virtual concert hall environment that I found so delightful. And, who knows, maybe if BACCH were more commonly used, some musicians would make the surround elements musically effective.

This view also should be contextualized by saying that I would consider BACCH4Mac to be a “Type 3” product, which are major game-changers addressing fundamental issues of audio. These probably only come along every few decades. That BACCH4Mac is a fundamentally new thing, and yet works with minimal side effects, is unusual and impressive.

BACCH4Mac comes to the market at a price that is quite reasonable in high-end terms. It has few downsides, if any (after all you can turn it down or off for any recording). It addresses a real issue for audio as we know it and does this for all existing stereo recordings, i.e. it doesn’t require new equipment or a change in recording technology. I do think it could encourage a refinement of recording technique, if engineers used it as part of the mix/master process, because then they would really know what data they are putting in those bits. I hope that happens, but even right now BACCH4Mac is a legitimate breakthrough.

In addition to streaming, 2go’s 2x 2 TB-rated SD card slots also enable the combination as an audiophile-grade music server, solid-state being the preferred storage medium for sound quality. The 2go’s SD storage capacity has been tested up to 4 TB (at the time of writing).

2yu securely connects to 2go, adding optical, S/PDIF coaxial and BNC (50 and 75 ohms, respectively) digital outputs, plus a cleverly integrated, highly flexible USB-A output giving a wide range of connectivity options. Owners of Chord Electronics’ Hugo M Scaler can also upscale the output (before passing to a DAC), taking sound performance to the next level.

The 2go/2yu combination is readily updatable with over-the-air firmware updates and ships with Chord Electronics’ latest 2go update (v. 1.5.0), which introduces new radio-listening and SD card album playback features, plus improved stability. The new firmware follows the release (in May) of the latest version of Gofigure, Chord Electronics’ set-up and configuration app companion.

The 2go/2yu combination is easily controllable using any one of several popular UPnP control point apps for both Android and iOS devices; Gofigure adds additional set up convenience, management features and a library playback option.

The 2go/2yu also benefits from gapless audio, DoP/Bit Perfect support and AirPlay support, and is fully DLNA-compliant (server/renderer). 2yu boasts 2,000 MIPS (million instructions per second) of processing power, automatic downsampling (for use with sample rate-limited legacy DACs), plus a low-jitter audio phase lock loop.

2yu is handmade in the UK using aircraft-grade aluminium and features four polychromatic spherical controls governing output selection, power, mute and dim functions.

Price and availability

2yu is available now priced at £449 (It requires a 2go, priced at £995).

The Roon application has three different, yet complementary, parts. The main part is the Roon Core. This is the section of Roon that does all the processing and interfacing. When using Roon, the Core section must be active at all times and should be on a computer with multiple processing cores, as well as a solid-state storage drive for the app itself. I’ve had my Roon Core (actually the desktop version, which is a combination of the Roon Core and Controller) on an Apple MacPro desktop, titanium trashcan model, for several years now.

Roon’s Core can also be installed on its own dedicated computer, and Roon even sells a “Nucleus” stand-alone computer that is specifically configured to run Roon. Roon offers two versions, the Nucleus ($1459) and the Nucleus Plus ($2559). You can also install the Roon Core application on one of 17 different Intel NUC computers that Roon has approved for Roon Core installation. Prices for these range from around $300 to just under $1000 for a NUC10i7FNx with case and solid-state drive. How hard is it to build you own NUC to run Roon? Here’s a quote from someone after a build: “It took literally 49 seconds to install and after that simply run Roon, select the core (which popped up immediately), and copy my music files to the internal 1TB SSD I installed.”

The other two parts of the Roon playback application are the Controller and the endpoints. The Controller app is the interface part that lets users make Roon sing and dance. It can be installed on any Android or iOS phone, Windows or Mac desktop or tablet, and offers all the control functions for Roon. An endpoint is any playback device that Roon supports. In my Roon system I currently have 16 endpoints, which includes four Raspberry Pi’s, three DACs connected via USB to my MacPro desktop, two DAC/streamers, several portable players, and a host of iOS and Android devices. Because I can, I have all my Roon endpoints connected via CAT 5 Ethernet, but Roon supports Wi-Fi (and AirPlay) as well as Ethernet endpoints.

Roon can be purchased one of several ways. You can get monthly, yearly, or lifetime subscriptions. Recently Roon raised its lifetime subscription rates, but did not discontinue them, although lifetime subscriptions would not be capable of supporting Roon long-term. Current rates in the U.S. are $12.99 for monthly, $119.88 for yearly ($9.99/per month), or $699 for lifetime subscriptions.

What’s New in 1.8—Seek and Ye Shall Find

I’ve been using computers to reproduce audio ever since I acquired my first Apple Mac Performa 600, back in the final quarter of the last century. l learned early on about folders and iTunes’ need for them. Some music-player applications still use folders, but one of the refreshing aspects of Roon is that you never need to use or even care about folders. Once you’ve designated which drives or folders on drives you want Roon to incorporate into your music library, any changes to those folders will be duly noted by Roon’s regularly and automatically updated database. What this means for a Roon user is that it no longer matters where your music is physically located. Be it on your hard drives, or in Tidal/Qobuz, or in your Dropbox, Roon supplies multiple ways of finding it.

And what do I mean by “multiple ways?” Of course, you have the ubiquitous magnifying glass icon, which lets you put in any words you wish, but that methodology has been around since the first build of AOL. Roon offers several other ways to find music. In its “Genres” page, you have types of music groupings, with the most populated categories closer to the top. For me “folk” and “classical” have the most releases. If you go into a genre category page, you will find listings of all your albums in that genre. Below the album list is an artist list. When you click on any of the performers, you get taken to that performer’s page, which will have all the albums by that artist in your collection. And on each artist’s page you will find a discography, which lists, with links, all the artist’s albums. Another new feature on the artist’s page is “Compositions,” which takes you to a list of all works penned by the artist. Going back to the Genre page, below the artists list is “New Releases” section. This includes new albums by any of the artists already in your library. Below this is the “Recommended Albums” section that includes releases by related artists that you may or may not have in your library. This section uses metadata from other Roon users with similar musical tastes to compile its listings. Below this, Roon has a short list of radio stations available through Roon Radio that play this genre of music. Finally, the last section on the page lists subgenres. For “Folk” there are 19 different categories, including Acid-Folk, Anti-Folk, and my fave, Work Songs…and each subgenre has sections similar to the main Genre page. One Roon user I know uses the phrase “going down the rabbit hole” to describe his late nights of search-inspired Roon-enabled musical forays.

Back in the days when LPs ruled the earth, whenever I contemplated buying a new album, I’d spend a lot of time perusing the back cover, looking for connections with artists and performers whose work I was already familiar with to determine whether I wanted to buy the album in hand. Unfortunately, until the latest version of Roon, digital music playback applications did not have the means to replicate the amount of data on the back of a record jacket—or the means to utilize that data. The latest version of Roon has made major inroads into this dilemma. Of course, Roon has always made extensive use of links. On earlier versions of Roon, all the performer links were light blue instead of black type, which made it easy to find them. Blue links also made it clear that not all performers and sidemen had links. On Roon 1.8 most of the blue links are gone, replaced by a far more elaborate and detailed connection scheme. Now a click on any performer will be a link to that performer. For an example I will use Paul McCartney’s latest, III. On the album page, next to the tab for the tracks listing, you have “Credits.” When you click on it, you will find several sections complete with links. The first section is “Credited On,” which lists all the musicians credited and what instruments they played. Each one can be clicked on, which will take you to their artist page. Below “Credits” is “Composers” which lists all the credited songwriters, with links to their other work. Below “Composers” is “Production” which lists engineers, producers, cover designers, and even photographers (if credited). A click on George Martin takes you to all the albums he had a hand in producing. The section titled “influencers, followers, collaborators, and associated with” will lead you even further afield from our original selection, III. During the course of examining these links I discovered that Greg Kurstin, who’s listed as one of III’s producers, also worked on Jeff Black’s Birmingham Road album. I’m a huge Jeff Black fan, but I didn’t know of this connection. Roon’s links can teach you stuff.

Classical music listeners have, since the first version of the  Gracenote search service, been limited in the ways they could search for their music. Four text lines, dictated by Gracenote’s limited display capabilities and metadata categories, led to the need to search for Bach under “performers” as well as other nonsensical queries. Roon 1.8 changes that. In Roon you have far more metadata categories for searching. Looking at Bach’s Brandenburg Concertos played by Il Giardino Armonico on Das Alte Werk label, next to the Classical category is “Concerto.” If you click on it, it will list all the concertos in your collection. There is also a “Chamber Music” category as well “Symphony,” “Vocal Music,” “Keyboard,” and perhaps a few more categories I haven’t discovered. Of course, if you want to search by composer, Roon has all composers in your library listed in the “Focus” section.

Roon’s Home page now has a lot more information about its owner’s listening patterns. Roon knows I have 2471 artists, 5683 albums, 67,482 tracks, and 193 composers in my library. Below that Roon lists all my recent playback activity. Scrolling farther down the page reveals three “New Releases for You,” which currently shows McCartney III, The Beatles Getting Better All the Time, and the Rolling Stones Turning Blue and Lonesome. Further down the page, the next section will tell you how much time you’ve spent listening through Roon. In the last four weeks I spent 57 hours and 43 minutes. Roon also breaks down what percentage of the time I spent listening to different genres, and provides the four most-played artists and four most-played albums. It also has a Genres section, Top Artists, Top Albums, suggested radio stations, and at the very bottom, several curated playlists provided by Roon.

Given that my library contains 5683 albums, when I select “My Library” and “My Albums,” scrolling through them would be a very slow search option, but Roon provides a more streamlined way with the Focus search functions. This feature offers more selectable subsets based on almost any category that has metadata. Genre has 18 different categories. Release Date is divided into decades, beginning with the 1940s. Performers lists every artist in your libraries, the same goes for the Composers and Production categories. Other filter options include “Played in the last,” “Added in the last,” ”Album star rating,” “Album type,” “Label,” “Format,” “Sample Rate,” “Bit Depth,” “Storage location,” and finally “Inspector,” which includes another whole bunch more categories. Any combination of search filters can be used. For example, I can choose “Grateful Dead,” “Live,” and “MQA” to find the live MQA-encoded Grateful Dead files…which brings up the 50^th Anniversary Workingman’s Dead on Tidal.

Roon’s Signal Processing Customization Features

Digital Signal Processing (DSP) can with some DACs and digital-reproduction systems sometimes produce a better final result than a bit-perfect file. I know of one DAC, the Khadas Tone Board, that has its most linear response with DSD64 files. With Roon, it was easy to designate that music I send to the Khadas Tone Board will all be transcoded into DSD64. Roon’s DSP capabilities also include headroom management so if you have files that were recorded at too high a level, they can be lowered a couple of dBs, so they do not clip your DAC. There’s also a clip indicator that can be turned on (it does nothing to the signal, so if you prefer no changes to the levels you can still see if a track causes clipping.) The “Sample Rate Conversion” section is where you can alter the format and bit rate of your files. You can also specify the Sigma-Delta modulator, enable native DSD processing, adjust the settings of the PCM-to-DSD filter, adjust the DSD-to-PCM gain, parallelize the Sigma-Delta modulator, as well as a few more adjustments. Each endpoint in your system can, and probably will, have its own particular optimal settings. You can also build your own preset filters. Why would you do this? My own example of a custom filter was a little something I built when I reviewed the Focal Arche DAC/headphone amp. The Arche reversed the channels on my DSF-format DSD recordings, so I built a preset that reversed channels for all DSF files played through it.

Besides DSP adjustments Roon also has provisions for extensive equalization for transducers and headphones. Roon has built-in filters for Audeze headphones and Headphone Crossfeed. With the parametric EQ, you can build and save EQ for every endpoint, headphone, or speaker system if you wish. If you are a devotee of the “Harman curve,” instead of a flat frequency response, you can make nearly any headphone adhere to that specification by building and then saving an EQ filter set for that earphone.

I regularly see the question asked by audiophiles, “Does Roon sound better than X, Y, or Z?” I also see many responses to this question that state unequivocally that “X, Y, or Z,” when playing one particular track, sounds better or worse than Roon. And such responders may be right; on their system, with their current setup, X, Y, or Z could sound better than Roon to their ears. But using one sample, where there is no way to determine that both files were identical, only proves that in that one case, in that one setup, the tracks sounded different enough for a listener to make a value judgment. Given the number of variables affecting streaming-music sound quality, to say unequivocally that any particular streaming service or playback app is universally superior to others, in my opinion, lacks credibility. But I will state, without a bit of irony, that compared to other playback apps Roon offers more ways to improve or screw up the sound than anything short of a complete digital audio workstation.

Are there any downsides to Roon? Sure. The first downside is that if Roon does not support a streaming service, you can’t use Roon with it. So, no Apple Music, no Amazon HD, and no Spotify through Roon. Also, Roon requires that your system be set up a particular way that may or may not be compatible with the way you have configured your own systems. If you do not adhere to Roon’s “best practices,” you will find that it may not work as smoothly as it should. Trying to run Roon Core on an uncertified computer can result in less than optimal performance, with slow load times and, occasionally, music drop-outs, stuttering, or an inability to find all the endpoints in your system. So, yes, there are many ways to make your Roon experience into an unpleasant one. But if you follow Roon’s “best practices,” Roon almost guarantees that you will have no issues with Roon’s performance.

Streaming Music’s Promise Almost Fully Realized

If you have read all the way through this article, either you have been seriously contemplating giving Roon a try or are already a Roon user who’s in the process of exploring the newest Roon version. In either case, I would expect that you will find the latest build comes the closest to realizing the promise and full ergonomic potential of digital music. Unlike most playback applications, which give you one or two ways to search for music, Roon supplies a multiplicity of search options and methodologies to spider through your music collection. That is huge. Instead of forcing you to do it “its way,” Roon offers users many different ways to explore their music collections, so they can choose the one that works with how they want to find their music.

When you add Roon’s technical capabilities and features, which include MQA Core unfolding, headroom management, sample rate conversion, EQ filters, the ability to build and save custom filters and presets, a clip indicator, and the ability to connect with almost every DAC, streamer, or endpoint in your home system, controllable on any phone or tablet, you have a 21^st century playback app that makes it painfully obvious that every other playback app is still anchored to the 20^th century. In short, if you aren’t using Roon, you aren’t getting close to the full ergonomic potential of your digital music libraries. 

The Sunlight upgrade is made possible because the PS Audio PerfectWave DirectStream DAC is one of the few DACs on the market that is fully programmable, by means of its FPGA (Field-Programmable Gate Array) core processing engine. This flexible architecture allows every parameter that controls the DirectStream DAC to be configured and tweaked.

With the Sunlight OS, the DirectStream DAC will now accept quad-rate DSD via its I²S input. By precisely controlling the clock timing of the signals in the various stages of the circuit, noise and jitter are significantly reduced. The sonic results of the Sunlight upgrade are a greater sense of resolution and space, a more natural tonal balance with improved top-end extension, better micro and macro dynamics, and a much more involving and engaging musical presentation overall.

Sunlight OS for the PS Audio PerfectWave DirectStream DAC can be downloaded free of charge by clicking on this link. Sunlight OS for the DirectStream Jr. can be downloaded at this link. In addition, Sunlight can be purchased pre-loaded onto an SD card (for the DirectStream DAC or USB stick (for the DirectStream Jr.) for $29 by clicking here.

“Our open platform enables partners to bring the best of their experiences to the Sonos system and our mutual customers,” said Ryan Richards, Director of Product Marketing at Sonos. “Qobuz has been at the forefront of high resolution music streaming, and we look forward to customers enjoying their music with the clarity, depth, and room-filling sound of Sonos.”

In 2013, Qobuz became the first music service to offer 16-bit FLAC streaming on Sonos. And now, it is continuing to expand access to higher-resolution streaming on Sonos by introducing 24-bit streaming, compatible with most products on the Sonos S2 platform, which supports up to 48 kHz/24-bit audio resolution. This new integration builds on Qobuz’s continued expansion of hardware partnerships, including the addition of Hi-Res compatible hardware on the Android platform several years ago.

Qobuz has always catered to the audiophile and the audio-curious market, with its expert curation, exclusive editorial content, liner notes, download store, and world-class sound quality. This expanded experience on Sonos will make premium Qobuz streaming capabilities accessible to a wider audience of music lovers. Qobuz has over seventy million tracks and is adding more in full Hi-Res quality every day.

Qobuz 24-bit Hi-Res streaming is available on Sonos in Austria, Belgium, France, Germany, Ireland, Italy, Luxembourg, Netherlands, Spain, Switzerland, United Kingdom, and the United States.

For those audiophiles concerned with how much compensation gets back to their music’s creators, published comparisons have Tidal delivering better per-stream rates than Apple, Google, Deezer, Spotify, Amazon, or YouTube. When asked about Qobuz payouts, a representative responded, “The main difference Qobuz makes in terms of royalty payment is that it offers—and promotes—its download option. Song downloads pay out a much higher percentage than song streams, so Qobuz helps to keep money in artists’ pockets.”

I’ve had a subscription to Qobuz since the 2018 Rocky Mountain Audio Fest. I also have a subscription to Tidal. Their respective apps are quite comparable in terms of their ergonomics and the sites themselves. Both require some “mine detection” (that is, clicking on stuff just to see what happens), and the Qobuz heart icon on top was a puzzler at first; it turns out that’s how you get to the music you’ve “favorited.” Speaking of favorites, one issue for anyone who already has a Tidal subscription: How do you export your favorite albums and tracks that you’ve found in Tidal over to Qobuz? This problem can be solved with Soundiiz which is a platform that transfers playlists and favorites from one music service to another for a small monthly fee.

Obviously Qobuz’s catalog offerings differ from those of other streaming services. According to its website, Qobuz has 40 million tracks and over 2 million hi-res files, but its offerings are not as deep into urban pop or and do not feature it as heavily as Tidal. Qobuz’s weekly email newsletters include new jazz, classical, folk, and international titles. As you might expect, Qobuz does not have exactly the same library as Tidal. When I ran Soundiiz to transfer my favorites, Qobuz only had about 85% of them. If I want to listen to the new remastered Rolling Stones Beggar’s Banquet, I can only find that on Qobuz, while The Beatles’ White Album is only available in hi-res via Tidal.

As to the thorny question of which service’s hi-res tracks sound better, once you level the playing field by using a DAC that is equally adept at handling FLAC or MQA files, the sonic differences, when I have heard them, have been a result of different masterings rather than one streaming service’s hi-res delivery being inherently superior to the other’s. How good is hi-res via Qobuz? Good enough that I could hear the print-through from the original tape via Qobuz’s 96/24 version of “Walking Blues” from Taj Mahal’s first album, which is something I’ve never heard from prior its masterings, be they digital or analog.

Giving audiophiles another hi-res streaming option can only be a good thing, and Qobuz certainly delivers hi-res streaming with elegance and continental verve. Bonjour, Qobuz. And good luck…