New NUC with Intel HD 5000 Graphics. NUC -> HDMI -> Xbox One (pass through) -> optical Toslink -> Denon AVR 3803 5.1
Installed BIOS update (latest available on NUC download page... 24 I think?).
Installed Windows 8.1 and all updates.
Installed all drivers suggested by Intel Driver Download utility. A few installs show as "failed" but that seems to be an issue with the utility, as all drivers do seem installed per Device Manager. I can particularly confirm that the Intel HDMI Audio is installed and working. I did try the below with the default Microsoft driver, but had the same behavior. I also tried with and without the Realtek Audio driver, but that shouldn't matter since I don't want the audio to go out that device (seems to only have analog out?)
Installed Windows Media Center.
Testing AC3 programs (digital broadcast, recordings, mkvs, and WMC setup test) all fail to produce output from center channel or surrounds. Left and right ONLY.
Tried the same with KODI / XBMC - same result. Audio works great, but all sources are downmixed to 2-channel only.
When I check sound devices, Intel HDMI is default, and it shows the Xbox One as supporting Dolby Digital. The configuration button only lets me select stereo speakers, but as I understand, that is normal? (I don't have anything to compare with.)
Based on prior threads, I have tried disabling legacy boot (as if that would matter). I have tried all bitstream rates, although again that should not matter. I have tried all combinations of exclusive and disabled all other enhancements fully. I have made certain that DVD auto volume is disabled in WMC (also shouldn't be the issue anyway, as KODI/XBMC does not produce surround sound either).
What are my next steps? I haven't had issues with a Cable box in this configuration, but I guess I should try my other PC with ATI video card. If the ATI machine works, it clearly is an Intel issue as I suspect.
Seems like the Xbox is telling the NUC that it supports DD, but the NUC isn't sending anything but 2-channel PCM, ever. Unfortunately I can't see much on the Xbox One side and I don't have an HDMI receiver to test with. But the Xbox One is playing 5.1 audio for videos and games played on the Xbox One. I tried DD and DTS encoding for the Xbox -> AVR, but that doesn't matter either (and doesn't with other input devices). If I had realized that the NUC didn't have an alternate digital audio out I might have looked elsewhere, but fortunately the Xbox One performs HDMI -> DD / DTS pretty well so far.
Please advise. If there are any steps for eliminating possible culprits, let me know. Many thanks in advance.