"It has already been noted in previous reviews that the professional market often offers products that may also be of interest to the 'ordinary' consumer. In Japan in particular, home systems often consist of a mix of consumer equipment and (vintage) professional items."
"Benchmark was founded in 1983 and started building professional audio equipment."
"The goal, from the outset, is to build sound-transparent equipment of the highest quality. The employees are musicians, audiophiles and audio technicians. So sound quality is top notch."
HPA4 vs. LA4
"The HPA4 and LA4 are preamplifiers and largely identical. The HPA4 also has a built-in headphone amplifier."
"The Benchmark HPA4 and LA4 preamps deliver a very high quality neutral and transparent signal."
"Developed from a professional focus on sound reproduction, they bring the essence of the recording closer to the listener."
"The AHB2 might look small and lightweight, but thanks to its clever engineering and power supply implementation, this little fellow could still deliver 190 Watts in 4 Ohms and 100 Watts in 8 Ohms, while maintaining an undetectable noise floor and distortion."
"For the craziest folks out there, you can even bridge two pieces together for ~580 Watts in 4 Ohms and 380W in 8 ohms."
"Thor almighty! This thing has some amazingly thick panels all around it, adding a level of confidence and refinement. It looks plain and industrial, but I really dig its minimalist body."
"You know what I like the most about it? Its bullet-proof protection systems!"
"Fault conditions silently mute both output channels in order to protect the speakers and amplifier from any damage."
"I somehow forgot ... blasting 380Watts of power into my KEF Reference 3 after pressing the play button. A microsecond didn’t pass and both AHB2 engaged their protection circuits and muted themselves without causing any harm to my loudspeakers."
"For almost a year now, AHB2 saved my speakers twice."
"The key words with AHB2 are: world-class detail retrieval, absolute transparency, lightning-fast transient response, an open wide soundstage with a very precise layering and positioning of the notes around the listener, all tightly controlled with an iron grip, never sounding too mellow, sluggish or all over the place."
"The highest compliment I can give to AHB2 is that I purchased not one, but two units with my hard-earned money. These weren’t loaner units and this wasn’t a sponsored review and you can draw your own conclusions."
"The Benchmark Media Systems HPA4 preamplifier is an exceptionally transparent and well-designed audio device."
"I found it to be an extremely neutral reference point that allowed me to hear more of what a connected speaker or headphone was actually doing and, in turn, how much my existing electronics were adding to the sound that I was hearing in my reviews."
- Carlo Lo Raso, Co-Editor, Secrets of Home Theater and High Fidelity
"Benchmark’s HPA4 is the first item of audio kit I have encountered that peels apart the ying and the yang of audio to expose the fault line between those of us for whom measurements are all that matters… and those of us that approach audio from a more emotional, less scientific direction. But in another sense it might also bridge the divide."
HPA4 Driving the Audeze LCD-5
"It had been the arrival of Audeze’s latest flagship planar headphone the LCD-5 that had prompted me to ask if I might borrow an HPA4."
"With the LCD-5 being a statement 14 Ohm/90db design, I felt I owed it to Audeze and myself to try driving the headphone with an amplifier whose specs suggested that it could easily cope with the requirement for current."
"The LCD-5 and HPA4 made an impressive partnership."
"On more energetic material, such as Marcus Miller’s M2 album from 2001, and the aptly named track Power, the LCD-5 showed that the HPA4 couples deep reserves of low-end grunt with a good level of dynamic expression. At loud but not silly volumes, the boom and snap of Miller’s slap bass technique had timing and tonal qualities that to my ears – alas, I do not have Miller’s talent but I do play bass – sounded uncommonly real through the LCD-5 headphone."
"I’d encourage anyone in the market for a high-end headphone amplifier to audition an HPA4."
"It is a device that achieves stellar measurements, yet sounds excellent too; evidence that the science-based approach can deliver high musicality."
"The HPA4 can drive pretty much anything, its resolution is truly remarkable, and you will likely hear your music with an acuity as never before."
The HPA4 is not just a "Reference Stereo Headphone Amplifier"; it is also a "Reference Line Amplifier" with "Relay Gain and Input Control."
"The fully balanced relay-controlled gain stage applies up to 15 dB of gain or up to 127.5 dB of attenuation for a total range of 142.5 dB. There are 286 volume control steps in precise 0.5 dB increments."
"During my first day of HPA4 listening, I noticed that every digital and analog recording ... sounded cleaner, better sorted, and more macrodynamic."
"The HPA4's sharp-focus specificity is something I associate with recording studio sound but almost never encounter in home systems."
"The THX-888 headphone amplifier board "is a unity gain (current) amplifier with feedforward error correction." Feedforward error correction is also used in the AHB2 power amplifier."
"With most headphone amplifiers, the tires go flat trying to drive HiFiMan's Susvara open-backed planar-magnetic circumaural headphones.
"The HPA4 exhibited no difficulty driving low-sensitivity, low-impedance planar magnetics."
"I had a feeling the Benchmark's absolute clarity coupled to the Susvara's legendary resolving powers would finally show me what the album's producers heard."
Abyss TC Headphones
"The Benchmark-Abyss combo really clicked for me. It gave me a fresh, intriguing look at my most familiar recordings."
ZMF Vérité Headphones
"I recommend you audition the Vérité closed-backs. They were my favorite music-listening headphone with the HPA4."
After a month ...
"Spending a month with the HPA4 forced this old triode-tube lover to first acknowledge, then accept, and finally enjoy a new type of engagement, one that satisfied my engineering mind and my audiophile lust to look and listen into the hidden nooks and distant corners of every recording. Thank you, Benchmark."
As a line preamplifier, the HPA4 performed almost identically to Benchmark's superb-measuring LA4, which Kal Rubinson reviewed in January 2020, so I will refer you to that review. This report therefore focuses on the HPA4's behavior as a headphone amplifier."
"The headphone amplifier's frequency response was flat in the audio band and down by just 1 dB at 200 kHz. With the very low output impedance, the response into 300 ohms was identical to that into the high 100k ohms load, and there wasn't any audio band rolloff with impedances as low as 10 ohms."
"Both the response and the superb channel matching were identical at lower settings of the control and from the unbalanced headphone output."
"From balanced inputs to balanced headphone output, the Benchmark had extremely low noise, with the power supply–related spuriae in its output close to –130dB, even with the volume control set to +15dB. With the volume control set to unity gain, the noise floor was 12dB lower!"
"The THD+N percentage was extremely low throughout the audio band into both 100k ohms and 300 ohms."
"I concluded my report on Benchmark's LA4 preamplifier by saying it was the widest-bandwidth, widest-dynamic-range, lowest-noise, lowest-distortion preamplifier I had encountered at that time. To those virtues, the HPA4 adds equally superb headphone outputs."
"When the folks at Benchmark suggested a review of their HPA4 for Tape Op, my first reaction was, “Isn’t this aimed more at the audiophile market?” Benchmark’s Rory Rall replied that I should consider its use as a reference-grade monitor controller, with a world-class headphone amp built-in. He recommended I pair it with my Benchmark DAC3 B digital-analog converter and use it to drive my Benchmark AHB2 power amp."
Four Years Experience with the AHB2
"When I previously reviewed the Benchmark AHB2, I described it as being as close to a straight wire with gain as I’ve ever heard – “a silent transmitter of musical energy.” I stand by that description after four years of living and listening to it."
The HPA4 Allows the DAC to Run Wide Open
"The HPA4 is built on the idea of avoiding any sort of bit-stripping volume control in the digital realm. So a full-output DAC sends it line-level audio."
"The volume knob is a 256-step precision encoder, driving relays that engage resistors, in 0.5 dB steps."
"Allow me to rave about the HPA4’s built-in headphone amp. Designed using similar technology as the AHB2 and licensed from THX (Benchmark calls it the THX-888 Amplifier), this is the cleanest, quietest, most neutral headphone amp I’ve ever heard."
"The HPA4 has no trouble playing music dynamically and precisely through any headphones I own."
"I can’t think of anything else that will get you closer to the sound coming out of your sources."
"Combined with Benchmark’s DAC and power amp with excellent speakers and headphones plugged in, this is quite the monitoring chain."
"When playing music you love, it will fire all the pleasure synapses."
"In the areas of tonal neutrality and transparency, the B sounds like every other Benchmark I’ve heard, which is to say neutral and transparent. But the DAC3 also has new conversion processing, which is said to make for a 3.5dB increase in headroom above 0dBFS, in turn preventing the DSP intersampling overloads."
"This increase in headroom ... is said to result in subtly improved sound."
LA4 Line Amplifier
"Benchmark prefers to call the LA4 a line amplifier (which may be the more correct term because that is what preamplifiers in fact do: amplify the signal) and offers it in two versions: linestage only, and the identical linestage with an onboard headphone amplifier, called the HPA4."
AHB2 Power Amplifier
"Before properly introducing the preamp, however, it is worth the while to recall that the AHB2amplifier is a genuinely innovative design, even, if you will, revelatory, and it set new standards in having by a wide margin the lowest noise and distortion and the widest bandwidth of any amplifier on the market then or now."
"There’s a complete absence of any sort of artifacts or noise; on very clean recordings, the presentation is uncanny in its purity."
"The benchmark combination offers a full range of equipment that can hardly be topped, leaves nothing to be desired in terms of sound, and meets professional requirements without any ifs or buts."
"The HPA4 has the HIFIMan one hundred percent under control, eliciting neutral timbres, tons of spatial information and crisp dynamics."
"I connected everything the household had to offer in terms of speakers - Spendor S3 / 5, Ayon Seagull / c, Quad ESL57. It goes without saying that the American coped with the dynamic boxes with ease. But even the quads, which have some meanness on the part of their impedance, did not pose a challenge for the amp."
"Since the HPA4 arrived, I have rediscovered so many of my favorite works all over again with improved detail retrieval dynamics and transparency that it’s hard to pull myself away!"
"It drove my power hungry Abyss Phi TC headphones with complete authority, but it was still dead silent and nimble enough to amplify my easy to drive Focal Utopia headphones."
"Rarely have I come across such a wonderfully revealing amplifier that can drive many different types of headphones so darn well! The solid build construction and various controls make the $2,995 price tag seem a bit low based on the other headphone amplifiers in this market space."
"You’ll have a tough time finding a cleaner, quieter, more transparent line amplifier and headphone amplifier anywhere, at any price. I found it to be a new reference. Once I heard it, I could not live without it, so I purchased the review sample. The HPA4 deserves my highest recommendation."
"The HPA4 is the latest product from Benchmark Media Systems, an upstate New York audio manufacturer."
"We think very highly of the products that Benchmark and John Siau, the company's director of engineering, have been launching in the market - and I'm certain our readers share that opinion."
"Benchmark calls it a headphone amplifier, but it’s really two products in one, combining the LA4 Line Amplifier introduced in 2018, with a headphone amplifier. It is also based on the same THX Achromatic Audio Amplifier technology used in Benchmark’s acclaimed AHB2 power amplifier."
"With DAC, preamplifier and power amplifier, Benchmark knows how to build a bridge between the professional sector and home hi-fi. Very beautiful."
"If you value transparent, precise sound, but at the same time want a certain level of comfort and at least a little elegance, you are in good hands with the Americans."
"The DAC3, HPA4 and AHB2 are all characterized by their wonderfully transparent sound and their high degree of precision. At the same time, sufficient amenities are offered to offer adequate comfort. A successful mix."
"Going into this test, based on measuring previous Benchmark products, I expected excellent performance. The benchmark HPA4 shattered even that high bar."
"It brings such a high performance to the table that leaves no doubt whatsoever about its transparency. No stone has been left unturned to optimize audio performance of this device. Even obscure measurements like ultrasonic interchannel phase shift is nailed."
"And then we have tons of power without messing with balanced cables and such. Plug in any headphone and you are in heaven."
"The preamp performance is even higher still, breaking and shattering any expectation one would have in a lab instrument let alone a consumer hi-fi."
"It goes without saying that the Benchmark HPA4 garners my strongest recommendation for a headphone amplifier and preamplifier.It doesn't get better than this folks."
"TheHPA4combined with the Benchmark AHB2 power amplifier ranks as the quietest rig I've heard (or not heard). Even with the gain up to full with no signal, there is no hiss, hum, or buzz, even when I placed my ears within a in inch of the drivers on 89 dB sensitive loudspeakers."
"As a headphone amplifier, the HPA4 was first rate. Whether it was my most power-hungry headphones, which currently are the new Abyss Diana Phi, or my most sensitive IERs, such as the Empire Ears Phantoms, there was no added noise or lack of adequate gain."
"The BenchmarkHPA4exhibits virtually no noise, whether employed as a stereo preamp or headphone amplifier, and his highly transparent, with no audible colorations."
"If you are looking for a preamplifier/headphone amplifier that you can live with happily for a long time, you should consider the BenchmarkHPA4at the top of your must-audition list."