I'm still learning what albain is trying to do, but I think that previous comment of mine was probably incorrect. I think now that he just needs PCM to go through untouched. ReClock takes that PCM stream and outputs with WASAPI exclusive, so ReClock doesn't need fixing for that purpose, it's still taking a PCM stream, just like it would with a DTS .wav file. They're trying to do the same as with those DTS WAVs. For those, you output bit-perfect 44.1 kHz 16-bit stereo PCM and in your receiver, it recognizes it and decodes DTS 5.1 48 kHz.
I still think the chances are low, mainly because of driver support. Another thing might be that simply those formats cannot be bistreamed piggybacking a PCM stream, or that if they do, that PCM stream needs to be set to a specific configuration (like DTS WAVs have to be set to 44.1 kHz 16-bit stereo). Did you try tweaking ReClock's WASAPI output to 16-bit? I don't know how ffdshow is sending the PCM, but output should match that. ReClock will tell you "(bit-exact)" when you're doing that.