Topping LA90 Power Amplifier Review

After a couple of days listening to it in my nearfield system, I contacted Apos Audio to see if Topping offered an industry accommodation for a second LA90 and its PRE90. They did. But unlike firms that use brick-and-mortar retailers, Topping’s pricing does not allow for the usual 40% or 50% discount off list price. They offered a 15% discount. I took it. A second LA90 and a PRE90 arrived a week later.

The Question of Reviewer Bias

All my readers are human (I hope), and as humans we all have our personal biases. As a reviewer I am well aware of my own predilections. In the introductory video I did recently for The Absolute Sound’s YouTube channel, I enumerated several of them. Another bias I must acknowledge is that I have a different level of attachment to and affection for components I own versus ones that have been loaned for review. It’s the primordial mine versus not-mine, I suppose…and because I know myself well enough to recognize my inclination, I counter it by being even more critical of components I own than of ones that are loaned for review. Does that level the playing field? Maybe, but be forewarned that I will take some extra space to note all the LA90’s potential shortcomings.

Tech Tour

The Topping LA90 amplifier ranks as unique for several reasons. The first reason it is special is that unlike most new power amplifier designs from China and elsewhere, the LA90 is an Old School Class AB linear amp instead of a Class D or other digital variation thereof. Given its extraordinary specifications, I inquired about the nature of the design in terms of feedback. The response from Topping’s design team (routed through Apos Audio) was that “the feedback structure is similar to [that of] our headphone amplifiers. The S/N figure is obtained through careful designs of power supply, resistor choices, and other fundamentals of design goodness.” Well, ok, then…

The LA90 has more adjustments than your run-of-the-mill power amplifier. You can change the gain from 9.5dB to 19.5dB via a switch on the back of the amplifier. This switch puts a resistor in front of the main amplifier stage. Why would you want to lower the gain? Depending on your preamplifier’s gain, you may find that the lower gain puts the preamplifier’s output into a more linear region.

Even 19.5dB of gain is on the low side for a power amplifier. Most tend to hover around 26dB, and some like the Clones Audio 25P deliver 30dB of gain. When you couple the gain with the power output, which depending on whose numbers you use sits between 50 and 60 watts per channel in stereo into 8 ohms, you have what most would consider a lower-power amplifier, especially when compared to the power amplifier offerings from Krell or Boulder.

One way to get the LA90 up to a more respectable power output is to convert it from a stereo amplifier into a mono amplifier; both channels can be bridged together to make an amplifier capable of 180 watts into 8 ohms, according to manufacturer’s specifications. Now you have two mono power amplifiers capable of driving most medium-sensitivity loudspeakers successfully.

Inexpensive components (anything under $1000) usually come in the equivalent of a plain brown wrapper—a rectangular black or silver-metal project box. The LA90 avoids that pitfall. Its chassis is made of five separate CNC-machined aluminum sections (they don’t call it billet aluminum even though, like billet, it is machined rather than cast), designed to allow for maximum thermal flow, so that instead of a fan or solid high-mass heatsinks, the LA90 uses slotted heat fins that allow for air flow in a way that solid heatsinks can’t.

Topping is very much a “numbers shop,” by which I mean it prides itself on the outstanding specifications its products deliver. Even its least expensive DAC has numbers any high-end manufacturer would envy. The LA90 boasts a total harmonic distortion and noise (THD+N) of 0.00008% at 20 watts into 4 ohms. Count those zeros…that’s more than pretty good. Between its THD+N and published signal to noise (S/N) of 143dB in mono mode, you have an amplifier that ranks up with the very best power amplifier specifications, such as the Benchmark ABH-2.

Setup and Ergonomics

As I noted in the technical tour, the LA90 can be used several different ways. I’ve tried them all. First, I installed the LA90 in my nearfield computer desktop system as an integrated amplifier, with the volume control both in and out of the circuit. Used as a stereo amplifier the LA90 had no trouble successfully driving Audience 1+1 and Falcon LS 3/5A loudspeakers in my reference nearfield system. With more power-hungry transducers, such as the ATC SC-7 II, the LA90’s 50 watts were slightly less than what was needed. But when two LA90 amplifiers were used on the ATCs in a nearfield setup, there was enough current to power the SC-7 IIs nicely.

When used within arm’s reach as a desktop integrated amplifier, the LA90’s lack of a remote control won’t be too much of an inconvenience. But if you want to use the LA90 as an integrated amplifier in a room-based system, the absence of a remote could give you some additional exercise. (When used as a basic power amplifier with the volume disabled, the remote was, obviously, not an issue.)

When it comes time to switch the LA90 from stereo to monoblock, in addition to moving a switch you must attach a jumper cable between one pair of the amplifier’s speaker outputs. The supplied cable fits tightly, which is good, but its rigid strain-relief collars have to be carefully angled so that the cable doesn’t either stick up in a way that partially blocks other cables or down to contact the shelf surface under the amplifier.

Another ergonomic quirk: The LA90 amplifiers in mono mode can get hot and are better off positioned with as much space as possible around them. That’s because they rely on thermal cooling systems to direct air laterally through their chassis. If you must put them side by side, I advise leaving open space around them and elevating them on footers to allow airflow under the amplifiers to reduce internal temperatures.

The external power supply for the LA90 is almost as heavy as the LA90 itself. It’s a beefy 64 volts and 4 amps. It also gets warm during operation. Its AC power cable employs a simple two-prong/figure-8 connection. And while you can get some beefy AC cables with that termination, they are not as common as the usual IEC kind. I used the stock AC cords, which were long enough to keep the power supply away from any other cables and in a well-ventilated spot. I know that for some folks the idea of an external PS rather than an internal one is “cheaping out,” but given the LA90’s thermal design I can’t help but feel that putting the power supply in a larger chassis with the rest of the amplifier would have merely increased the price and decreased the amplifier’s performance.

I use balanced cables whenever possible, so I had no issues with the LA90’s all-balanced input configuration. But if you have already invested in some high-quality single-ended RCA cables, you may have to get some RCA-to-XLR or RCA-to-TRS adapters to interface with the LA90.

Even when the amp is in bridged mono mode, you can, if you wish, have the volume control in the circuit. While it’s relatively uncommon to see a volume control on most power amplifiers sold in the U.S., my experience with Ali Express-sourced power amplifiers is that including a volume control (usually an Alps Blue Velvet) on a basic power amplifier is common in China. If you plan to run an over/under amplifier setup with one LA90 amp set in mono on each tweeter and a bigger stereo or mono power amplifier on the midrange/woofers (in a two-way system with separate speaker connections for the tweeter and midrange/woofer), being able to adjust the LA90’s output would make it easy to balance the levels between radically different gain-level amplifiers, if needed.

Sound

My current power amplifier options include several Class A Hood-based designs, a Pass 150.8 class A/B, Texas Instrument chip amps from LSA and Clones Audio, as well as several other Class D amps using Sanyo chips or ICE modules, but nothing in my collection sounds quite like the Topping LA90. It is simply the most sonically invisible power amplifier I’ve heard and comes closest to the ideal of a straight wire with gain.

Even with my most sensitive loudspeakers, a pair of 93dB Omega single-driver prototypes, the Topping’s base noise level is so imperceptible that even with my ears nearly imbedded in the driver I hear no sound whatsoever, with no difference between the sound of the amplifier when turned on or off. Nothing. You’re probably thinking: “Big woo! I can get the same result with my XXXX amp and my XXX speakers.” But, trust me, it’s not the same. The LA90 disappears more completely than any amplifier I’ve ever heard before. By disappearing, I mean that it sounds as if there is less of a sense of “amplifier” affecting the sound. Instead, the music is presented in a way that feels like a more direct connection between the source and my ears.

I have a quiet listening room. It measures only 35dB on my sound-pressure meter in A-weighted mode. In the past I’ve rejected some very fine gear because it was simply not quiet enough for my room. The LA90, even in high-gain mode (which was how it was used, except when installed in a nearfield setup), added absolutely no additional noise, and when coupled to the Schiit Freya S in passive mode, I could turn up the volume controls to maximum and still hear absolutely nothing through the Spatial X-2 loudspeakers (86dB sensitivity) even with my ear an inch away from the tweeter. If it wasn’t for the LA90’s front-panel LED, I wouldn’t have known it was turned on!

Ranking the most impressive aspects to the LA90’s sound, the first would have to be the additional ease in listening. The lack of low-level noise imbues the entire soundstage with a quieter background than I’m accustomed to hearing, even with quiet amplifiers like the Pass 150.8, which only produce the slightest hiss (you need to put your ear extremely close to the tweeter to hear it). There were several heretofore-undecipherable throwaway lines in the background of some Billie Eilish’s singles that I listen to regularly. Through the LA90 I could make out words that even through headphones had previously been a blur. Was I surprised? You bet.

The second most impressive sonic characteristic was the LA90’s clarity throughout its frequency range. Even in the lower midrange and upper bass, which usually have the most issues with homogenization, sluggishness, and murkiness, through the LA90 these frequencies had a level of detail and lack of constriction that made music refreshingly easy to hear and decipher.

In his recent review of the Pear Blue Audio Odar turntable, Robert Greene writes: “As it happens, this is true about audio in general. Low-distortion electronics also sound non-aggressive within a given bandwidth.” I agree. While still lightning fast, the LA90’s upper frequencies don’t get hard or brittle even during dynamic peaks. I noticed this clearly on my own live recordings. The violins and brass during fff passages of my recording of Mahler’s Third Symphony from Mahlerfest 2013 (co-recorded with Jerry Bruck of Posthorn Recordings) remained musical even during massed dynamic peaks. Flutes and piccolos were sweet rather than piercing.

This Mahler recording also demonstrated the extremely accurate image placement within the soundstage. Not only was lateral placement precise, but the layering of instruments, with the brass slightly higher (they were on risers) and farther back on the stage, was easy to hear. The LA90 does the 3D thing (on recordings that contain the spatial information) as well as any solid-state Class AB amplifier I’ve heard.

Vocals through the LA90 have a remarkable clarity coupled with natural warmth. The Punch Brothers’ latest release Hell on Church Street has a tune called “Orphan Annie.” After an acoustic bass introduction that captures the essence of acoustic bass tonality, Chris Thile’s vocals begin. Through the LA90/Spatial X-2/JL Audio Fathom f112 system, the sound of his voice had an arrestingly realistic character. I’ve been around Chris at workshops and jams, so I know what his voice sounds like; this recording, through this system, had a level of veracity that could, in J. Gordon Holt’s words, “produce goosebumps.” Also, if you listen in a quiet room, you can even hear the rustling of clothing as the musicians move around the microphone.

Although I use a pair of JL Audio f112 subwoofers with the Spatial X-2 loudspeakers, I have the system set up so that the Spatial X-2s receive a full-range signal without any crossover truncating their low frequencies. Turning off the JL subs let me hear how the LA90 was supporting the bass. Again, I was struck by the clarity, especially in the midbass region, where the low ranges of synthesizers combined with guitars and keyboards compete and conflict on many pop releases. On Finneas’ “Partners in Crime” from Blood Harmony, the fluttery synth part had a level of texture and inner detail that was easy to luxuriate in.

I like Finneas. On his Optimist album, “the 90s” is not only a great song, but also a torture test of how well a system can reproduce the sound of distortion. At 2:10, what sounds almost like a sawtooth waveform on the synthesizer begins. Distortion as percussion. As the distortion builds, on some systems the sound gets increasingly foggy and vague. Through the LA90 the distortion sounds clean. What? Even as Finneas adds additional layers of distortion, each layer retains its own identity instead of merging into a miasmic whole. At 2:53, the distortion halts abruptly, and Finneas solo voice begins, bringing a soothing feeling of calm to the mix.

Competition

Yes, I realize that choosing a power amplifier isn’t the same as a horse race. Or is it? At a certain point it does come down to: “What can I get for how much?” For the price of one LA90 you can get one Schiit Audio Vidar ($799), which is also a Class AB solid-state amplifier that can be bridged for mono. It has double the power of the LA90 at 100 watts into 8 ohms, but not quite as good SNR figure at 115dB down. If you want to consume more energy, have less power, worse specifications, but get that Class A sonic character, Schiit also offers the Aegir ($899), which is a Class A version of the Vidar.

If we look at what is in the price range of two LA90s ($1798), the competition increases. The LSA Warp One amplifier I reviewed in Issue 331 lists for $1495. It has completely different topology, being a Texas Instrument switching power amplifier, but it shares the LA90’s variable-gain feature, offering four different gain options via DIP switches. The Warp One also offers both single-ended RCA and balanced XLR inputs. In terms of sonic differences, both are exceedingly clean and detailed, but in comparison the LA90 delivers a slightly warmer upper bass and lower midrange with some loudspeakers, such as the Falcon LS35/A. Both amps had excellent low-level detail and overall clarity, to the point where the winner in a sonic shoot-out would depend more on how a particular loudspeaker interacted with each amplifier rather than differences in intrinsic sonic character.

Although in a completely different price class from the LA90, the Pass 150.8 ($7500), has been my primary reference amplifier driving the Spatial X-2 loudspeakers. When I first hooked up two LA90s, I wondered whether the combination would be in the same league in overall sonic quality with the Pass Labs amplifier. While the two amplifiers had similar levels of detail and soundstage capabilities, the Pass had more grunt and a greater sense of power in reserve.

Although I no longer have it to compare directly to the LA90, the Benchmark AHB-2 ($2999) shared some sonic similarities with the LA90. The ABH-2 was equally quiet and equally good at placing instruments accurately in the soundstage’s lateral plane, but I don’t think the ABH-2 had the same level of depth recreation or quite the same level of low-level resolution. Through the LA90 I felt listening into the mix was just easier and my engagement level deeper.

Summary

More times than even I can remember, I’ve read audio component reviews which conclude with “I bought it!” This is usually the final coup in most reviews, showing that the product was so good even the reviewer could not resist it (at a 40% to 50% discount). That’s not going to happen here. This sort of “big reveal” has already had its balloon popped in the third paragraph.

For most of my power amplifier needs, one or two LA90s have been almost ideal. Obviously, I do plan to keep the pair of LA90 power amplifiers I already own, and perhaps, as time passes and they become more available on the secondary market, I might even pick up another one or two, just because….

If you have mid- to high-efficiency loudspeakers that you love, you may find the LA90 to be an ideal power or integrated amplifier for your system, too. I can easily see a single LA90 as the “summer amp” in high-efficiency horn systems. I would not recommend that owners of 2-ohm Apogee Scintillas or Theil CS3.5s, or if you have a large room with only moderately efficient speakers, run out and buy a pair. Some loudspeakers simply need more power than even two LA90s can give.

But unless you have a friend who has already purchased an LA90, your chances of hearing one or trying one out before you buy are pretty much nil. If you are intrigued by the LA90’s potential, you’re going to have to take a leap of faith (with a 45-day return window from Apos or 30-day from Amazon) and buy before you try, just like I did. So, while I would usually finish a review by recommending you hear a product for yourself, that’s going to be difficult with the LA90. However, if you’re feeling lucky (like the signature dialog from the film The Mask), I encourage you to take a leap of faith and give the LA90 a try. I seriously doubt you will be disappointed by its capabilities or performance.

Specs & Pricing

Type: Solid-state Class AB amplifier
Output power: 50Wpc into 8 ohms stereo, 180W into 8 ohms mono
Inputs: Three XLR/TRA inputs
Output impedance: <3 ohms
Dimensions: 20.5 x 22 x 9cm
Weight: 2.7 kg
Price: $899