Palm-sized headphone amplifier with stylish design that delivers a genuine vacuum tube Hi-Fi sound with high clarity, ideal for vocals and classical music. It provides a headphone impedance of 16-300 Ohm, total output power of 180 mW x 2 (16Ohm load) or 22 mW x 2 (300Ohm load), and frequency response of 10 Hz-65 kHz. The body of the amplifier is made of sturdy alloy and features a micro USB connector that provides powering for the built-in 1800mAh lithium-ion polymer battery with lifespan of 16-18 hours. A USB cable (for battery charge only) and audio cable are both included. Total harmonic: <0.1%. Signal-to-noise ratio: ≥80dB. Dimensions: 125.6 x 78 x 16 mm. Weight: 150.5 g. Black colour.