I just sold the DAC.
But to answer your question, yes, you can run the DAC with two sources, three actually. Optical, Coaxial and USB. There's a switch that toggles between (I think) USB and non-USB, and auto-sensing for Optical versus Coaxial. I might have wrong what the switch does, but you can definitely run three different digital inputs into the DAC (I've tried them all).