"The HPA4 is Benchmark’s latest headphone amplifier. This amp is unusual in that it features a THX-888 Achromatic audio amplifier, which is claimed to reduce distortion by 20–40 dB through a patented feed-forward design, resulting in the world’s most linear amplifier. In addition to the THX amp circuitry, Benchmark has gone slightly nuts (in a good way) with the volume control, offering 256 levels in 0.5 dB steps via an array of relays. The idea is to limit noise and allow the user to dial-in volume precisely."
"The HPA4 is a high-voltage, high-current design to allow low-sensitivity headphones to work well. In addition, the damping factor is high (near zero ohms output impedance), with the aim of sounding the same with low-, medium-, and high-impedance headphones."
"I thought the HPA4 sounded as good as any headphone amp I’ve heard for dynamic headphones, and it might be the best of the lot depending on your circumstances."
"The HPA4 is exceptionally good at presenting a layered, dynamic, yet relaxed sound. You can hear these rich results on, for example, Eliza Gilkyson’s Hard Times in Babylon (Red House), where the instruments not only are clearly differentiated but also sound fully rendered, as live instruments do. You also can hear the overtones of each instrument as they decay, which makes them sound more real."
"... wish the review sample didn’t have to go back."
- Tom Martin, The Absolute Sound
"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."
"There are many things that come into play when putting together a hi-fi system, one of which is synergy."
"After the arrival of the Benchmark Media Systems AHB2, I immediately thought of the matching HPA4 that colleagues Jaap and Yung were very pleased with."
"The key question, of course, was whether the HPA4 would really provide an audible improvement."
"Well you bet! The synergy between preamp and power amplifier is nothing short of magical, not to mention the DAC3 B that I got from importer Helios for the occasion."
"Not only a few curtains disappear, the whole window is gone."
- Geoffrey Vanhouwaert, Alpha-Audio
"The Benchmark AHB2 is a very fine sounding, easy to live with, zero-maintenance power amplifier that has enough power for most systems. If more power is needed, two amplifiers configured for mono can provide it. The decision to purchase the review sample and make the Benchmark AHB2 a new, long term reference took over a month of listening and comparisons."
"The outstanding musicality of the Benchmark AHB2 takes some time to convince the listener of its wholly musical presentation. This subtle excellence assures long term satisfaction."
-10 Audio, Perfect 10 Award