Sure my second paragraph was more a general commentary about DAC quality, I could have written some different things in the posts. Using the receiver/amps DAC plus doing a long run, that's good enough reason to use digital, sucks that the live encoding is not always available.
One other little thing : some higher end onboards chips do support DTS Connect, and the vast majority of time it is disabled due to licensing reasons (a small cost must be paid by the motherboard vendor). It is enabled on some higher end motherboards.. and I'm pretty sure I read you can "unofficially" run the full featured driver!
By quick googling the DSX's manual says this, though I don't pretend to fully understand it (just plug a RCA into a jack?? but I guess you can use a trivial and cheap RCA to mono jack adapter)
"You can also use a coaxial cable for a S/PDIF connection. Just plug the coaxial RCA male connector to the S/PDIF-Out combo jack and connect the other end into the coaxial S/PDIF input on your decoder. ASUS Xonar DSX"