"THX has patented a novel amplifier design, THX AAA Technology(TM) and Benchmark Media Systems has turned it into a new power amplifier – AHB2. The design is called Achromatic Audio Amplifier. Achromatic may mean colorless or neutral or without modulation. The AHB2 is an attack on current amplifier design. It’s basically an AB amp with a class H power rail arrangement."
"A low power Class A correction amplifier ... runs in parallel with the regular AB amplifier ... and corrects ... non-linearity in the transition stage."
"The AHB2 is a class AB amp – but could easily be mistaken for a class D with its very compact dimensions. The small size is made possible by the compact switching power supply."
"The AHB2 has a resonant zero-voltage switching power supply. The switching is carried out at frequencies well above the audio band to reduce any audible artifacts from the power supply. Switching power supplies are much more efficient, and smaller, than linear transformer based supplies."
"The AHB2 power supply is regulated and very efficient in combination with the H Class rails. Benchmark claims that there is no sagging in internal voltage during high loads or when line voltage dips."
"The amplifier has a spectacular frequency response of 0.4 Hz to 200 kHz. This means that the AHB2 will amplify the high frequencies present on high res digital files."
"So is there a sound signature to the AHB2? Since THX calls it Achromatic we can assume that they were not aiming for a warm and sweet tubey sound – and this is not what it delivers. The sound is indeed neutral and exact without being sterile or clinical. Colorless? Not really. The amp will send through the sound palette of the source component and disc/file without stripping any color away."
"The Benchmark AHB2 is a solid foundation for an audio system. It is very quiet with extremely low distortion."
"The AHB2 is so good it will immediately expose weaknesses in your system. It requires a very good pre-amp ... which should output a balanced signal."
"Medals to everyone and a rebel princess to the AAA Technology inventor!"
- Toby Tingskog, dagogo.com
Benchmark's Rory Rall shows a storm trooper the AHB2 power amplifier at the NAMM 2016 Show, and explains the new THX AAA Technology. Rory waved his hand and was heard to say: "These are the amplifiers that you are looking for."
"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