AHB2 Technical Analysis - Robert E. Green, The Absolute Sound
AHB2 - "A Technical Tour de Force Without any Question"
"The Benchmark amplifier is quieter than any other amplifier I am aware of."
"It has noise of around 110 dB down relative to 1 watt, and since it has 100 watts of power, the signal-to-noise ratio that is relevant to resolution is around 130 dB. Not quite enough for 24 bits in theory—130 dB corresponds to 21.5 bits—but in practice enough for anything."
"Each bit gives one 6.02dB of dynamic range. So 130dB of dynamic range corresponds to between 21 and 22 bits. This means that the amplifier is very unlikely to be a limiting factor in terms of signal-to-noise ratio—or equivalently, resolution."
"Do you hear noise from your speakers when there is no signal present? If not, making your amplifier quieter will not make any difference."
"But if you have for instance very high sensitivity speakers so that one watt is going to correspond to a lot of sound (e.g., over 100 dB for Klipschorns), and you are not going to go beyond that one watt very often, then the quietness of the Benchmark, of noise being 110 dB down from one watt, may come into play more emphatically."
"Most amplifier manufacturers give noise down from full output level, typically something like 110 dB down. If an amp has 100 watts, that is 20 dB above one watt, then the amount by which noise is down from one watt is maybe only 90 dB. So with a speaker with 100 dB sensitivity will put out 10 dB of noise. K-horns usually hiss a little at you when they are not playing if they are fastened up to a turned-on amplifier."
"In any case, no matter what kind of speakers you have, you are going to find the Benchmark dead quiet."
"The Benchmark also has extremely low distortion—among the lowest around and surely far below known thresholds."
"The Benchmark can be used in bridged mode, to give 400 watts into 8 ohms (actually 380W is specified). That ought to be enough for most applications except in extremely large rooms."
"The Benchmark AHB2 amplifier is a technical tour de force without any question."
- Robert E. Green, The Absolute Sound, April 2016
Also in Reviews
AHB2 Review - Mike Prager, Future Audiophile
"For years, the audio world acknowledged one main contender (at least at sub-five-figure pricing) for the quietest, cleanest, most neutral power amplifier around. That was the Benchmark AHB2, whose specifications are still, for all practical purposes, unsurpassed, even by today’s excellent Class-D amps."
"10 years after its release, the Benchmark Media Systems AHB2 stereo power amp is still a standard-bearer in clean, neutral sound in the audiophile world."
"I greatly enjoyed having a pair of AHB2s in my system – their purity, neutrality, and seemingly unlimited power provided a clear window on the music and a lot of joy."
"I especially appreciated the AHB2’s smooth, well-integrated treble, free of splashiness or grain, and its natural reproduction of the human voice."
- Mike Prager, Future Audiophile
AHB2 Review - Constantine Soo, Dagogo
"The AHB2 bridgeable stereo amplifier ... was the topic of a recent discussion between American electrostatic panel speaker manufacturer Sound Lab’s president, Dr. Roger West, and me."
"In our discussion, he related his highly positive experience in driving even his largest, $55k Majestic 945 panels with the $7,000 pair of Benchmark Media AHB2 monoblocks, along with the $3,050 LA4 Preamplifier and factory XLR cables."
"Dr. West described the AHB2 as a class AB design using “feed-forward distortion reduction [thus removing] any possibility of pushing the margin of safety of a standard feedback loop, used in most amplifiers, into an unstable oscillatory mode.”"
"He further shared with me that “this is of most concern on powerful musical transients. The distortion of the amplifier in the balanced mode is astonishingly low even at just below the clipping level of 380 watts.”"
"The prospect of the AHB2’s specified distortion level of 0.00015% or lower when at full volume is comical at first glance, but upon actual audition the impact of the achievement is very audible from medium-high listening levels and upward."
"It was unlike any other sub-$20,000 amplifier I have auditioned."
"My audition of the Benchmark Media AHB2 amplifiers underscores the reason Dr. West is so taken by it, and confirms the design is best described as a watershed moment in the high-end audio industry."
- Constantine Soo, Dagogo
DAC3 Review - Jerry Del Colliano
"Benchmark is a stalwart brand in pro audio, but has carved out a very respectable niche in the audiophile world with their diminutive but powerful components."
"The audiophile world sometimes looks to the professional audio world for enlightenment, especially on the digital side of things, and Benchmark Media is one of the companies that we put high on a pedestal."
"They are hardcore digital engineers freezing their asses off in upstate New York as they come up with some pretty innovative ways to get your varied digital sources sounding as much like the master tape as possible. Thank you for your service, gentlemen."
"If you really want to hear what your music sounds like in today’s streaming-driven world, this might just be the DAC that you need to test out."
- Jerry Del Colliano, Future Audiophile