HPA4 - Review - John Gatski, Everything Audio Network
"One of the most transparent audio products I have ever heard at any price"
"Marvelously open and clean"
Relay-Controlled Volume and Input Selection
"This new custom designed, 256-step relay volume control HP amp/line stage is incredible in its transparency and ability to get out of the way when listening to accurate sources with accurate headphones. Just as impressive, the line stage delivers volume control that many an esoteric analog or digital preamp could only dream of."
THX Achromatic Audio Amplifier (AAA™) Technology
"The HPA4 is a co-design by Benchmark and THX, Ltd. using the THX Achromatic Audio Amplifier (AAA™) technology that was implemented in the Benchmark AHB2 amplifier a couple of years ago. According to Benchmark, the THX AAA™ reduces harmonic, intermodulation and crossover distortion by 20 to 40 dB to guarantee a realistic and fatigue-free listening experience."
The Benchmark AHB2 Power Amplifier Introduced the AAA™ Technology
Listening Impressions
"I cannot stress enough how the HPA4 just gets out of the way so you can listen to your music and the components in your chain. The HPA4 is sonically neutral, distortion free and deeply dynamic. At any level, it will let the music shine through with no added color."
More About the Volume Control
"The rotary relay gain control features 256 steps in 0.5 dB increments. The HPA4 includes four independent 256-step attenuators: two for the left and right headphone outputs, and two for the left and right line outputs."
Remote Control and System Integration
"The HPA4 includes IR remote control and can be operated using the optional Benchmark remote. You can use it with Benchmark’s highly rated DAC3 converters, as well as any other source with an analog output. When paired with a Benchmark DAC, a single remote control will operate both units."
Touch Screen
"Besides the impressive performance, the HPA4 is Benchmark’s first product with a LCD touch screen that enables most functions of the unit. The screen provides access to advanced features such as balance control, input level offsets, input names, screen dimming, remote control, and function locking. Help screens explain the special functions. The HPA4 includes independent on-screen mute buttons for the headphone and line outputs. Both can also be muted with the volume knob or with the optional remote control."
Low-Level Listening Tests
"The key to a superior volume control is how it sounds when you turn it down ..."
"... you should be able to hear the gentle room reverb of drum cymbal or ringing piano note decay as you turn the volume down."
"The Benchmark HPA4 with its precision relay and ultra quiet amp section, sounds the same at reduced levels as it does when it is turned up."
" When I turned down level, I could still hear the exquisite, precise imaging of the brushed drum cymbals, the snare rim shots and the tasteful Steinway piano notes. I am talking about real musical accuracy, not some euphonic coloration definition of being musical. I am talking about the way music sounds live in a great room, dimensional and full. That is what I hear from the HPA4."
Headphone Listening Impressions
"For headphone listening, I had a long list of demo cans, including my AKG K702 Anniversary, Sennheiser HD-650, AKG K812, Oppo PM1 planar magnetic headphones and the Audeze LCD-XC... the HPA4 handled all of them with ease."
"The Benchmark HPA4 is one of the most transparent headphone amps I have ever heard — at any price. Just as impressive is the line stage, which delivers volume control that many an esoteric analog or digital preamp could only dream of."
Using the HPA4 as a Preamplifier
"The line output was routed to a Benchmark AHB2 amp and a pair of Martin Logan Impressions electrostatics.
"As a line-stage the HPA4 was quite adept ... I found myself relying on the HPA4, as well, for other product reviews because it is so transparent. From an accuracy standpoint, it sounds better than $20,000 preamps I have heard. And oh-so clean."
Conclusion
"To say I am impressed with Benchmark HPA4 would be an understatement. One of the best HP amps and line stages I ever have heard in terms of transparency and accuracy. The ultra-low distortion, its ability to drive any headphone, plenty of connections and the cool factor of the LCD screen menu selection: it is darn near perfect."
"Based on my impressions, the Benchmark HPA4 receives two Everything Audio Network Stellar Sound Awards. One for its headphone amp and one for its line stage. Folks, it is that good."
- John Gatski, Everything Audio Network
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