Massdrop offers the FX Audio PH-A1 Headphone Amp in Black or Silver for $49.99 plus $7.75 for shipping. That's $25 off list and the lowest total price we could find. It features a brushed aluminum housing, 10Hz to 30kHz frequency response, 80mW to 1,000mW output power, stereo RCA and 3.5mm inputs, and 6.35mm output. Deal ends January 15.
Note: It's estimated to ship February 7.