Flame me if I missed this...
but I was looking at the pdf file and I noticed even though it says S/PDIF input, the "connection options" picuture only shows digital out to a digital mixer? Also on the oade baord doug said "I have heard the same rumor about it being a S/PDIF output. I pressed them for more and learned the reasoning was the S/PDIF connector is on the back with the RCA out while the front has the inputs. I really do not know but I do point out the headphone jack is on the front..." If it was I/O, wouldn't it be like the USB connector?
Typo or problem?
Edit: Opps, I guess you could do RCA > Mixer

But the Doug comment is still a little troublesome.