My multich audio takes a few forms. I use SACD, DVD-A, Bluray for discs. There's some multich audio on youtube I've run into, but not a lot. There's the Atmos converted stuff on Apple, Tidal and Amazon for streaming afaik. You might be able to download your multich music files onto a thumb drive for playback via your bluray player (multich files not usually supported by an avr IME but don't know about these latest Sony models). I wouldn't play stereo files via all ch stereo, I'd just use a surround upmixer (Dolby or DTS....does yours have a Sony 360 feature?).