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