Nuforce HAP-100-BLACK Preamp and Headphone Amplifier (Black) A preamplifier stage providing 5dB of gain with zero negative feedback for fatigue-free listening A single-ended Class A headphone amplifier stage (a design topology long held by audiophiles to be the last word in headphone reproduction) A linear power supply employing a toroidal transformer, large capacitor reserves and high-speed regulation for fast, clean power to all circuits A signal-to-noise ratio in excess of 100dB Four low-noise, stereo RCA inputs