"Benchmark is known for digital-to-analog converters (DACs), but it's recently been expanding into other products, including the first amplifier to use THX's new high-efficiency, all-analog technology, and the new SMS1 minispeaker. The SMS1 is a rebranded and somewhat improved version of the Studio Electric SE Monitor. As designer David Macpherson, owner of Studio Electric, told me, Benchmark's engineers were able to refine the circuit-board layout and acquire parts with tighter tolerances. I thought the SMS1 pulled off the tough trick of sounding neutral yet very detailed and spacious."
- Brent Butterworth, Sound Stage
"It’s ... been a while since I have been this excited about an audio product."
"Audeze LCD-2C, Quad Era-1, Brainwavz Alara, Sennheiser HD650 ..."
"It’s the first time when I have heard the headphones mentioned above to their full potential. In the first minute my jaw dropped ..."
"From my perspective this is the best headphone amplifier I have ever heard. It’s no competition really."
"It’s not cheap, I can give you that. Is it worth it? That is up to each and every one of you, but if you really want the best amplifier out there, an end game amplifier…this is it."
- Dan-Alexandru Gheorghe, HeadMania.org
"The HPA4 combined 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 Benchmark HPA4 exhibits 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 Benchmark HPA4 at the top of your must-audition list."
- Steven Stone, HomeTheaterReview.com
"Today, is a very special day for me, since I believe I am hearing the best overall performance out of my headphones."
"The distance performance-wise between HPA4 and my second-best headphone amp is Night and Day!"
"This headphone amplifier and line pre-amplifier receives my highest recommendation and scores the highest rank in my book."
"It spoiled me so much, that for the past 3 days I’m waking up at 5 A.M. so I can listen, tap my feet and head-bang just a little bit more. I for one, started saving for one, I’m sorry but I can’t go back to regular amps."
"Without a doubt Benchmark HPA4 is an end-game, top of the line headphone amp – it’s The One to rule them All."
- Sandu Vitalie, SoundNews.net