Pyle Home PHE5AB Bass Boost Portable Headphone Amplifier, Black Designed for High Impedance and Low Sensitivity Headphones - Boost Volume and Reduce Battery Drain of Portable Players Easy to Carry and Use In The Outdoors - Built-In Rechargeable Battery (Charged Via USB) Increases Your Headphone's Bass & Sound - Robust Metal Casing For Everyday Use New Amplifier IC with Higher S/N and Lower Distortion - Ultra Low Signal to Noise and Distortion Specification Portable Headphone Amp for iPod, MP3 Player, Laptop or Mobile Phone