HPA4 - Review - Tom Martin, The Absolute Sound

"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

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