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.