I would recommend not using your apple TV to stream music. I have tried this on my system and after some research, I believe apple TV up/down samples everything to 48khz, not sure the bit depth. I actually have a airplay receiver in the rack to listen to music from streaming services when the song isn’t on my music server.

With that said, J rivers MC has a performer store which lets you stream music. It’s the best sounding streams I’ve hear, even though the bit rate seems lower than most. (with that said, that also has the best connection to the system since I can bypass windows mixer and send straight to an outboard dac so a perfect a/b isn’t possible with Spotify and MOG. Best i can get is airplay to airplay recevier, then optical to a simaudio dac, but i think MOG sounds signficantly better out of those two.