"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."
- Amir Majidimehr, Audio Science Review
"The AHB2 easily outperforms the DIY Hypex NC400 I had tested before which used to be the best amp I had tested."
"THD+N versus output level looks far cleaner than anything I have tested before."
"Intermodulation distortion versus power level shows the same story of clean power."
Signal to Noise Ratio:
(unweighted, 22.5 kHz BW)
Ch1: 130.286 dB
Ch2: 130.180 dB
-0.3 dB at 20 kHz
-3 dB down at 200 kHz!!
"Since this is not a switching amplifier, there is no filter there allowing the bandwidth to go to 200 kHz and beyond."
Stereo Power into 4 Ohms:
"We have 185 watts of power at incredibly low distortion of 0.00016%, besting the company specifications."
Bridged Mono Power into 4 Ohms:
"500 watts into 4 ohm! Stunning 0.00026% distortion at 500 watts!!"
"It goes without saying that the Benchmark AHB2 breaks new ground ... gets my strongest recommendation."
- Amir Majidimehr, AudioScienceReview.com