... headphone amplifier with many input options, which includes digital inputs from optical, coaxial, USB, and analog input from AUX IN/OUT. ... which is convenient for OPAMP rolling.Main Features:- PCM2906B, converts USB into a S/PDIF signal- CS8416, DA-receiver chip ... to manager inputs, outputs, and functions.- Flexible input and output compatibility. It has USB, optical, coaxial, stereo inputs, line out, ...