Auzentech i.Fuzen HP-1 headphone amp & battery case for iPhone 4

Proprietary Auzentech headphone amplifier technology Dual headphone output port for shared listening experience; supports both high and low impedance headphones 32 to 600 Ohm load impedance 113dB (A-weighted) signal-to-noise ratio ZX-Driver provides ultra-low distortion and max 180mW output power J-FET OPAMP provides vacuum tube-like listening experience Proprietary Auzentech headphone Sound Mode Selector provides optimized sound for your headphone Touch Panel volume control Impressive 1650mAh Li-Polymer battery with Smart Protection Circuit Four-step LED battery life meter and battery life check button Charging via USB port (from desktop PC or laptop) with supplied USB cable Pass-through sync with iTunes