[DDDamian]

Tested again :
- I had in the UI correctly selected "WASAPI: VSX-921-1 (NVIDIA High Definition Audio)" for both audio output and passthrough. If something else is used by XBMC, there is something wrong somewhere.
- Selection seems stable, as if i quit and restard XBMC, i'm still on "WASAPI: VSX-921-1 (NVIDIA High Definition Audio)" (but still without audio).
- Windows and XBMC are set to 7.1 speakers.
- Drivers are already up to date.
- Disabling in Windows (in the audio windows settings) VIA HDMI changed nothing. You have a log file of the result here.
- Passthrough seems to works (i had audio playing a file from a DTS file). It seems that problem occurs on non-passthrough audio.
- Some files when tested started with a VERY low frame rate (around2-3 instead of 24). Not this king of problem with previous version.
- This worked perfectly fine with the version just prior AE merge. You have a log file of the result here.

I see two issues in logs: the first, as mentioned, is that your nVidia is only reporting two channels, and it is still being hijacked by the VIA onboard. You need to disable that in the BIOS - not just in Windows. If you look at the device actually used it is the VIA, even though we request the nVidia per your selection.

The second is that one of the files has AAC audio - AAC is not decoded (yet) by AE - the only way it will work is if your receiver supports AAC natively. If it doesn't, as it appears, you will get silence or noise. We plan on adding AAC decoding along with DTS-wav soon.

EDIT: once you've disabled VIA in BIOS, d/l and run MonInfo and paste the report for your HDMI connection here - will tell me what the receiver/tv/nvidia EDID info is as reported via HDMI connection, including number of channels supported.