RME drivers have only one setting an are not really integrated with Windows. That is bad in some aspects but good fromSQ point as there is no mixer issue. Irrstective of what settings you choose DTS CD via SPDIF will play correctly.
However, I think using the analogue out is the real gain with this card.
I never tried WinAmp, but with JRiver Media Centre there is nothing I can do to preving it from playing DTC CD/files correctly. It just does it. I am encoding them as WMA lossless.
There maybe some plug-ins in WinAmp that are altering the sound path.
I just was not very active in last couple of months as I was concetrating on the new job and a rather complex personal project that I will be wrtting about when all bit come into place. Otherwise all is well.