I think it would be great if it was possible, so I could use my surround system to play music while I have guests. But I think Spotify has already been working together with someone else than Apple, to get surround sound for premium users it was a bit cheaper. But an app for the Apple TV would make my life easier, and they already have one for other Apple Products, so why not
I suggest you to post this idea in a special community section.
https://community.spotify.com/t5/Idea-Submissions/idb-p/ideas_submissions
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