Windows 10 audio configuration keeps changing from 5.1 to stereo at random

Question

I have configured my sound system in Windows 10 as 5.1, and can hear and test all 5 speakers individually without problems. Then, when I am playing a movie with VLC or working with my Unity application, Windows 10 keeps changing (seemingly randomly) back to Stereo, and often times 5-10 seconds later again back to 5.1, always with a 1-2 second delay (silence) during switching.

I have a Teufel Concept E and Concept 450 speaker system which have onboard sound cards. I have also tried using a Behringer FCA610 and Logilink UA0099 7.1 sound card connected to the sound system via optical cable and also with 3 single 3.5mm cables. Nothing seems to matter, Windows 10 arbitrarily change between stereo and 5.1 mode. I never had this issue with Windows 7.

If I configure the soundcard via Windows control panel (Speaker Setup screen), it often shows as being in Stereo mode, even though I just 5 minutes prior set it to 5.1! Sometimes it works fine for an hour, other times it happens after several minutes. I can't determine any rhyme or reason.

I have also tried using a different PC where nothing sound-related is running except my Unity application, and again the same problem occurs. One PC is Intel i7-8700, the other is an AMD Ryzen 7.

I tried installing Xear audio panel (suggested by Teufel) and changing to 5.1 manually, but this too sometimes resets back to Stereo mode, also seemingly randomly.

How can I lock Windows down to 5.1? Can I run some kind script that runs continuously and sets to 5.1? It is highly frustrating!

Answer 1

I called Teufel tech support and they said it's a known problem when connecting via USB with a fix on the way, but for now I should stick to using optical cable for the most stable surround sound connection. As mentioned in my question I had tried optical without success, but now I disabled all other audio adapters, including the Realtek onboard via BIOS, as well as removing Realtek audio manager software and Xear audio driver and now the problem seems to be resolved.