The Pass Labs 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 Pass Labs 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. Technical specifications Gain (dB): 8 dB; Power Consumption (W): 23; Output Power into 20 ohms: 3500 mW; Output Power into 300 ohms: 200 mW; Frequency Response: 10hz -100k (-1 dB); THD + Noise: < 0.005 at 1V out; Input Impedance: 50K Ohm; Output Impedance: < 2 ohms. Visit the Pass Labs website.