The InLine® Mobile AmpUSB HiFi DSD Headphone Amplifier is connected to a mobile phone via USB and is used for reproducing and amplifying audio signals. Headphones are connected to the unit via a stereo jack and the playback volume is adjusted via a rotary control. InLine® Mobile AmpUSB HiFi DSD Headphone Amplifier is an ultra-mastering grade digital audio playback system. It is capable of converting high resolution PCM audio (up to 384 kHz) and DSD audio (up to 128x DSD). The DAC allows you to bypass your mobile phone's soundcard or headphone output and send digital audio signal through the USB interface. With this perfect digital interface between your mobile phone and the music system, the sound quality is pushed to another higher level in your overall music environment.