AHB2 - Class A Recommended Component - Fall 2018 - Power Amps
In his listening tests, KR discovered "much more apparent low-level detail in already-familiar recordings"—a characteristic he credited to the Benchmark's evident noiselessness—and a tonal balance that "sounded more 'right' than any of [the other amps on hand]."
In measuring the AHB2 and attempting to confirm its specified very high signal/noise ratio, JA observed nonlinearities in his testing equipment that "haven't affected the measured performance of other amplifiers I've tested, but they were detectable with the AHB2's very low intrinsic distortion and noise." His conclusion: "an extraordinary amplifier."
'Class A' is Stereophile's highest classification for recommended components. Very few components receive this elite classification. Stereophile defines 'Class A' as follows:
"Best attainable sound for a component of its kind, almost without practical considerations; "the least musical compromise." A Class A system is one for which you don't have to make a leap of faith to believe that you're hearing the real thing."
"Benchmark describes its product as a 'reference Stereo Headphone Amplifier and Reference Line Amplifier with Relay Gain and Input Control', which should give you some idea of what's going on here, but only hints at the fact that this is actually two completely separate products packed into one relatively compact unit."
"The headphone section is powered by a power amp from THX, employing the same AAA (Achromatic Audio Amplifier) technology first used by the company in its AHB2."
"Benchmark's line amplifier uses relays for input selection, gain control and muting while four independent 256-step attenuators ... feed the the headphone ... and preamp outputs."
"As PM notes in his Lab Report, this design gives the HPA4 not only outstanding performance, but also rather impressive - to say the least - signal delivery."
"All of a track or two should do the trick, as whether with revealing headphones ... or used as a preamp, the HPA4 simply drops jaws with the sheer impact, openness and vivacity of the way it plays music."
"It was one of those real 'performer in the room' experiences and I was instantly transported back to the time I spent monitoring the recording as it was being made ..."
- Andrew Everard, Hi-Fi News, November 2018
"John Atkinson's measurements corroborated Benchmark's claim that the DAC3 is capable of "at least" 21-bit performance ..."
"Benchmark created an amplifier that more than matched the DAC3's dynamic range: the AHB2. Bridged to mono, the AHB2 has a claimed A-weighted dynamic range of 135dB ... it now sits in Class A of Stereophile's 'Recommended Components.'"
"With the DAC3 HGC and the AHB2, Benchmark seems to have achieved the lowest-noise, lowest-distortion system of source and amplification on the planet. The signals this combo sends to loudspeakers should be cleaner—truer to the source—than any other audio components can achieve."
"This article is unusual in that my goal was not to take the measure of a particular component but to determine whether Benchmark's entire low-noise system could resolve musical detail that a more typical audiophile system, with noise and distortion levels that are low but not as low, could not."
"The comparison system consisted of PS Audio DirectStream DAC and BHK Signature preamp and, variously, PS Audio BHK 300 and Pass Laboratories XA60.8 monoblocks."
"Through the Benchmark amps those quiet sounds were richer and more interesting. There seemed to be more going on in those quiet moments. It's harder to describe than it was to hear."
"Over the course of several days, I went back and forth between the Benchmark amplifiers and heard it every time. The difference didn't go away."
- Jim Austin, Stereophile