In1 RCA S/PDIF.
In2 Toslink optical.
In3 USB Audio Class 2.0 (no driver required on Mac OS X as of v.10.6.4 nor on Linux, driver required only for Windows).Any inputs from 1 to 3 can receive stereo audio encoded signal up to 384 kHz/Bit depth up to 32 compatible DSD over PCM.