AHB2 Review - Kalman Rubinson, Stereophile

"This compact, lightweight, cool-running, class-AB power amplifier is a real breakthrough in every way"

"When I unpacked the AHB2, I was impressed with its small size and weight: the non-rack-mount version is 11.04" wide by 3.84" high by 9.34" deep and weighs only 12.5 lbs. I was also impressed with a seriousness of design apparent in its features: The fully balanced AHB2 has, on its rear panel, only XLR jacks for signal input, plus a toggle switch that allows the user to select among three input-sensitivity levels. For output, the Benchmark amp offers a choice of traditional multiway connectors or a stereo pair of Neutrik NL4 sockets. A third Neutrik NL4 is provided for use when the amp is in bridged mode, which is selected with a second toggle switch."

"These features, along with the detailed manual and specs included with the amp, suggest that the AHB2's target market is the audio professional or the recording studio."

"... it was probably the AHB2's low noise level that revealed to me much more apparent low-level detail in already-familiar recordings. I qualify that statement with apparent because, after hearing the AHB2 uncover previously unheard subtle details, I found I could now hear them when I returned to my other amps. I suspect that, being newly informed of their existence, my ear/brain could more easily extract those details from the output provided all along by my other amplifiers. This made a much greater impression on me than any subjective awareness of a lower noise floor, per se."

"These surprising and delicious details were evident from the bass up through the midrange and extreme treble, which nonetheless remained silky and diaphanous."

"In addition to quantity of soundstage detail, the AHB2 was also "large" in power output. It was clear that this 100Wpc (into 8 ohms) stereo amp had all the power needed to drive with aplomb my Bowers & Wilkins 800 Diamond speakers to any reasonable level. At an SPL of 90dB, the B&Ws are of neither particularly high nor low efficiency, but JA has told us what makes them difficult to drive: ... there are current-hungry combinations of 4 ohms and –52° electrical phase angle at 62Hz and 5.3 ohms and –39° phase angle at 8.6kHz."

"That seemed to present no problem for the AHB2 ... I had to push the AHB2 to unreasonable and personally uncomfortable volume levels to get the least blink from one of its Clip LEDs"

"At first, I thought the AHB2 sounded less bright, and less full in the bass, than the other amps I had on hand, but after only a few days of listening I began to accept that it sounded more "right" than any of them. Now the treble wasn't so much un-bright as smoother and unaccented. The bass had all requisite extension and detail (see above), but seemed to be more naturally balanced with the rest of the audio band."

"As time passed and I listened more, I grew to love the AHB2's sound, and undertook the rewarding effort of listening through it to as many different recordings as I could. It was a great pleasure, as old friends, some already mentioned, smiled anew. Yes, I could hear the differences between the different amplifiers, and that's the point. This compact, lightweight, cool-running, class-AB power amp is a real breakthrough in every way."

- Kalman Rubinson, Stereophile

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