The AT-PHA100 Portable Headphone Amplifier from Audio-Technica is enclosed in all-aluminum casing to protect the circuitry and is designed to give headphones a rich, detailed boost throughout the sonic range with ultra-low distortion. It is equipped with both analog and digital inputs (1/8" and USB micro-B) and can be connected to several sources to provide better headphone quality for laptops, smartphones, recorders, and more.
Featuring a high-/low-gain switch, a machined-aluminum volume knob, and a five-stage sampling indicator for digital input, the headphone amp is compatible with USB 2.0 and uses an internal lithium polymer rechargeable battery for power. It lasts up to 14 hours when amplifying an analog signal and up to 6 hours when amplifying a digital signal.
Additionally, it comes with two rubber bands and a rubber mat for strapping the unit to a smartphone or other portable device. Also included are a 3.3' USB to micro-B (2.0) cable and a 3.9" audio cable terminating in a 1/8" gold-plated stereo mini jack on each end.