Sabaj Audio PHA2 Portable Headphone Amplifier Silver Color Build-in sabaj-patented boosting power module which increase input power from 5V to +-15V. Audiophile-Quality sound with good CNC aluminium cabinet 5V power input by Micro USB or power adaptor WIMA&SIEMENS capacitor used,Using TPA6120A2 headphone amplifier chips from TI RCA analog signal input for amplifier or active speaker connection