I'm a lifelong Mac user, but a gaming handheld has gotten me into some of these topics. I dual-boot SteamOS and Windows.

On SteamOS, my 5.1 stereo just works.

On Windows, apparently there was some software package called DTS Live (and/or Dolby Live) needed to wrap the audio stream in a container that the stereo understands. There was a time when there was a patent pool on the AC-3 codec (or something like that - I'm handwaving because I don't know all the details). So Microsoft stopped licensing the patent, and now you just can't use AC-3 on Windows. I spent an evening installing something called Virtual CABLE and trying to use it to juryrig my own Dolby Live encoder with ffmpeg… Never got it to work.

It's easy to fall deep into the tinkerhole on Linux, which has kept me away for a long time, but as mainstream platforms get more locked down, or stop supporting things they decide should be obsolete, it's nice to have a refuge where you're still in control, and things still work.

(Insert meme about the Windows API in Proton being a more stable target than actual Windows.)