AHB2 - "Conspicuous Only in Its Absence"
"Before she joined Jefferson Airplane, Grace Slick was in a band called The Great Society. They made an LP, Conspicuous Only in Its Absence, the title of which has stuck in my mind ever since I first heard it as a teenager. (The album also contains some killer psychedelic rock riffing, but that’s another story for another time.) That album’s title is a perfect description of how the new Benchmark AHB2 power amplifier fits into a studio monitoring system."
"After upgrading my monitors to Amphion Two18 speakers [Tape Op#108], I decided to look into modern alternatives to my circa-1980s Audio Design Associates (ADA) FET300 power amp. That amp, designed by ADA co-founder Albert Langella, is built like a tank and has served me without fail since I built my studio almost 20 years ago."
"Because they were designed for multi-room systems, Langella’s power amps were capable of handling very low impedance loads and were built into massive all-metal boxes. And in this lies the rub: Al preferred to use bigfans to keep things cool in the boxes."
"Over two decades of working with the ADA amp, I got used to the fan noise, and tuned it out. As far as audio quality, the amp offered very good low-level resolution and plenty of dynamic power. I thought it was the cat’s ass and didn’t even consider swapping it out, until I started reading descriptions and reviews of the Benchmark amp."
"The Benchmark AHB2 amp uses new technology from THX, the folks who bring you “certified” cinema sound systems."
"Benchmark took the THX technology another step by designing the amp to work in a lower-gain mode in a pro- audio setting. This allows for a very low noise-floor, because there is no gain wasted and then attenuated."
"The audio system shouldn’t add any noise. It should run in the background — a silent transmitter of the musical energy. In my listening tests, the Benchmark AHB2 amp did this."
"As soon as I unplugged the ADA amp and swapped in the Benchmark, it was clear how nice it was to hear less fan noise. I cranked up the monitor volume all the way on my Lynx Hilo [Tape Op #90] and confirmed there was zero hiss, hum, and other power line hash. I put my ear right to the speakers — still dead silent."
"So now, just from being in the system, the Benchmark had taken down the room noise (no fans) and lowered the monitor system noise floor from very quiet to silent."
"I then started listening to music and other audio — projects I recently completed plus favorite albums. I did this for several weeks, and I also took the Benchmark upstate and plugged it into my B&W 805 Diamond speakers there."
"In every case, I heard the amp as essentially transparent — a silent transmitter of musical energy."
"What did stand out was a very quick and precise quality to the bass, as if the amp is quicker on the draw than most, when it comes to moving the piston to move the air."
"I’ll describe the AHB2 as the sonic equivalent of a very sharp plasma display — full-featured, well-defined, and natural-looking, as if looking at a real thing instead of a digital image."
"Benchmark also sent me a DAC2 HGC [Tape Op #97] to test drive, and I coupled it with the AHB2 in my big listening room, driving a pair of B&W 808 speakers. This setup replaced a Benchmark DAC1 HDR and an Aragon 8008 amp."
"As happened in the studio, when I swapped the former power amp back in, the sound clouded up a bit, the stereo field narrowed a bit, and I found I wanted to turn the volume knob up a bit because things seemed somewhat muddier. To get back to The Great Society album title, the Benchmark AHB2 was very much conspicuous in its absence. My ears missed it!"
"As far as sound differences between the two Benchmark DACs, I couldn’t hear any on the big speakers in my listening room, but Benchmark claims a number of improvements in the DAC2 HGC."
"For me, the compelling case for switching to the DAC2 HGC is its feature set."
"I liked the feature set on the DAC2 HGC enough to buy it for my big listening room, replacing the DAC1 HDR. I bought the AHB2 power amp for my studio and have started filling the piggy bank to buy one for the big listening room. Paired with the Amphion Two18 speakers in the studio, the AHB2 is half of the new “Dynamic Duo.”"
- Tom Fine, Tape Op
"RMAF 2018 was really good, with significant numbers of attendees, and more new-product introductions than I remembered ever seeing there."
"Led by engineer John Siau and based in Syracuse, New York, Benchmark Media Systems has built a sterling reputation for making compact, well-engineered, moderately priced electronics that challenge the state of the art, both on the test bench and in the listening room."
"What I took notice of were the specifications: total harmonic distortion of less than 0.00006%, and a signal/noise ratio exceeding 135dB from 20Hz to 20kHz."
"If those claims are true, and there’s no reason to believe they aren’t -- Benchmark gear has always performed as specified on the test bench -- the LA4 should be about as transparent-sounding a line-stage as you can find at any price."
- Doug Schneider, SoundStage! Hi-Fi
"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