Just got the 'listen bug' again, I muted SPDIF and unmuted, decode flashed about 10 times (Stereo mix 'loopback' on/off/on/off/on/off/on), was not the above although its still wrong and has issues.
No idea how to fix it
I might try VAC in place of Stereo Mix again like I did about 2-3 years ago (ALC 889), even then it did the same (which is intermittent on start-up). No hardware though.
Muting an endpoint back then used to switch off APO's (could see DTS re-init), the current updated MS mute does not seem to affect apos.
Note the driver and all files have been updated several times.
Capture (Stereo Mix, hardware) ----> Microsoft loopback (listen to) ----> Render (SPDIF)
Capture (VAC, software) ----> Microsoft loopback (listen to) ----> Render (SPDIF)
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So I removed all APO's and extra data from ALL endpoints, and still get the same bug with Microsoft loopback. Their audio engine is pretty bad is multiple places.
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I can understand why so many professionals will use
ASIO, essentially to replace the Microsoft audio engine with something better......
Audio file any format (ends up as PCM) > Windows Audio Engine > Hardware.
Audio file any format (ends up as PCM) > ASIO > Hardware.
On-the-fly encoding | PCM > Windows Audio Engine (encoded) > Hardware.
Bitstream-Passthrough file >> Hardware.