Thanks for the file. I got some more info...
You know, I just got the DTS .wav file to work. I had to set manually my Vista output to Stereo, and then the DTS would be bitstreamed. So I think it's a side-effect of my channels not being changed automatically. Presumably, in your system the channels are changed to stereo automatically, so you didn't get the static when using WASAPI-exclusive.
I have now tested with a completely clean install of Vista 32, and still the same trouble! Tried just for the fun of it Catalyst 8.12 hotfix and (after another Vista full restore), 9.1. Nothing changed.
Well, I can at least suggest a work-around using ReClock. You can, in fact, bypass MC's audio playback chain completely and use DirectShow instead. What you need to do is:
1. Go to tools>options
2. Select "File Types" from the left-side list
3. In the list, for each file type you want to play back change the playback method from "Automatic" to JRiver
video engine(using DirectShow filters)
4. Select "Playback" from the left-side list
5. Under "Video" select "DirectShow video playback settings"
6. Make sure the audio renderer is set to ReClock.
7. Hit OK (lol I feel so patronizing putting that, but for the sake of being thorough..)
This way you can use the separate ReClock function (that you've said works for you) to automatically change the speaker config and WASAPI will handle changing the bit-depth/samplerate (which you've also said works for you).
After all that effort you deserve some results!