Fostex HP-A3mk2 USB DAC and Headphone Amplifier

The HP-A3mk2 is a desktop DAC and headphone amplifier that takes its power from the same USB-C cable carrying the audio, so it needs no wall adapter. It handles up to 192 kHz at 32-bit over USB 2.0 High Speed and also accepts S/PDIF on a rectangular optical input at 32 to 96 kHz, with an optical output that follows the input sample rate.

The headphone stage puts out 100 mW into 32 ohms or 20 mW into 300 ohms on a 6.3 mm jack, and will drive loads from 16 ohms up, with distortion quoted at 0.03 percent or less. RCA line outputs deliver 2 Vrms at 0 dBFS into 10 kohms or higher at 0.005 percent distortion. The chassis is 113 x 34 x 155 mm and weighs about 500 g; a 1 m Type-A to Type-C cable and four rubber feet are supplied.