Well, I've got both uncompressed WAV and APE rips of DTS sources (Brubeck, Moody Blues, Steely Dan, etc.). My config has changed over the months, but essentially what I mentioned before is somewhat accurate.
I'm doing no upsampling, just using the "source" selections, the MC DSP is OFF.
This AM, I did a quick "start-to-finish" to make sure I was accurate. One thing has changed which I didn't notice before. Now the RME driver auto-detects the discrete bitstream and I don't have to manually select "non-audio" on the driver setup. However, between songs, I still get that "static" as it "figures out" the signal. Manually choosing "non-audio" on the driver fixes that, so it's not totally automatic.
So whether I have a APE or WAV DTS source, playing via ASIO, it goes out as a discrete bitstream to the AVP which then plays and displays the DTS-only options (Music, Film or THX) available. The AVP shuts off all other surround mode settings and options when it detects a DTS or DD discrete bitstream.
HTH,
Mike