2023 Golden Ear: Krell KSA-i400 Power Amplifier

$36,000

A monster pure Class A amplifier, delivering 400Wpc into 8 ohms and a whopping 800Wpc into 4 ohms, the Krell KSA-i400 offers 164V peak-to-peak output voltage and 58V rms, with 62 amps of peak output current and a damping factor of greater than 800. Add to that 5400VA of transformers and 188,000uF of capacitance, and you can drive pretty much anything effortlessly. Although I am convinced that the engineers at Krell employed some type of alien technology or elvish magic, they insist it’s Krell’s patent-pending iBias technology/XD low-output-impedance control/Symmetry Maximization that makes the magic happen. It maintains Class A by using a new iBias circuit topology that checks current and adjusts bias to maintain a preset low current in a feedback design. Krell also implements an internet-based control-and- monitoring system to access power, temperature, balance, etc. from an app. The stereo amp simply sounded right. Like “I gotta get me one of these!” kinda right. The speed, agility, low-frequency viscerality (is that a word?), and dynamic scale screamed Class A on steroids. Yet it maintained the nuance and finesse, the midrange bloom, and high-frequency blossom that Class A delivers, without the power limits we have come to expect. In my review I said to “just buy it!” And I second that statement here. Golden Ear and well deserved. (339)