I had a proof-of-concept fix in 47928a8, but it was deemed "not nice" (which I actually agree with. I don't quite see a better solution though.)

@RomanPudashkin @cbjeukendrup perhaps we need to have a chat about this to discuss for which project we should prioritise it.

@cbjeukendrup I already have a prettier fix for this, where I put the channel change in the mixer (so the sound generation still runs on two channels, then the mixer uses that to fill two of the surround channels). I think this is better than trying to make all of the instruments and effects surround-capable.
There are still some device change glitches I wanted to fix and didn't get around to, but otherwise it runs fine. If that sounds good to you, I will create a pull request.

@Jojo-1000 That certainly sounds good! Would be great if you could open a PR with what you have so far, and then we can look into the device change glitches later.

@heisluft Can you check #17669 please if it fixes your issue? Thanks!

Hey @DmitryArefiev I would like to, however the actions of the PR don't seem to have produced a downloadable artifact and I don't have the ability rn to get a QT installation up & runnning, so I am unable to compile MU myself. Would it be possible to link me an artifact generated by CI?

@heisluft Here is the link to download the builds: https://github.com/musescore/MuseScore/actions/runs/5039329182
(To find it, on the pull request page, go to the "Checks" tab and click the Windows check, which should bring you to this download page.)

Thanks alot! The PR indeed fixes the issue. Looking forward to the release ^^

Also, I find the theoretical Possibility of surround mixes very intriguing, combined with musesounds it'd make for an even better cinematic scoring experience!