In bass clarity and authority and in midrange transparency, the Pass Labs HPA-1 is without peer.
The HPA-1 headphone amplifier was designed ground-up to become what we believe is one of the very best sounding headphone amplifiers available today. With low feedback, wide bandwidth and a direct coupled MOSFET output stage, this musical instrument drives even the most difficult headphone loads with ease, power and grace. The HPA-1 also functions as a line-level preamplifier that sonically rivals much higher-priced competition. The measured performance is superb and the sound even better.
Gain (dB) 8 db
Frequency Response 10hz – 100k -1 dB
Output Power into 20 ohms 3500 mW
THD + Noise < 0.005 at 1V out
Out Power into 300 ohms 200 mW
Input Impedance 50K Ohm
Output Impedance < 2 ohms
Power Consumption (Watts) 23
Unit Dimension (W x D x H) (In.) 11 x 13.5 x 4
Unit Weight (LBS) 14
As balanced headphone operation is the audio fashion du jour, it might be felt that Pass Labs's sticking with single-ended operation could work against the HPA-1. But regardless of circuit topology and the active devices, it's the sound quality that matters, and on that count the HPA-1 scores big-time. Yes, it's an expensive headphone amplifier; but I venture to suggest that, in bass clarity and authority and in midrange transparency, the Pass Labs HPA-1 is without peer.