I was expecting the usually 2 channel to 5 channel upmixing from my Chromecast GT, and surprised to see the AVR menu showing an "DD+" 5.1 audio input.
I still can't explain why their movie rentals are still in 2 channel.
I use the Firestick 4K and see DD+ as well.
I'd like to understand where this is supported across YT. I'm a premium member so I'll have to check if any surround music is available.
Edit:
https://support.google.com/youtube/answer/11904456?hl=en#:~:text=5.1%20in%20YouTube%20is%20supported,device%20supports%205.1%20for%20YouTube.