The FiiO E1 is a headphone amplifier, specifically designed for use with Apple"s iPod and iPhone. It is the first headphone amplifier in the world with in-line remote control functions. The FiiO E1 has a built in high quality headphone amplifier IC manufactured by Texas Instruments. The FiiO E1 uses the line out signal from the iPod/iPhone, so it provides better sound quality, and is able to drive high impedance or low sensitivity headphones! With the in-line control function, you can easily control the playback of the iPod/iPhone from the E1 Amplifier. The FiiO E1 will bring you better sound quality and a more convenient playback experience! Powered by the iPod/iPhone (no charging or battery needed) Traditional Apple white style, with a built-in clip, you can clip it onto anything