no 5.1 sound with Apple TV

Check your Apple TV’s audio settings, it may be switching everything to stereo. Make sure your Apple TV is connected via HDMI, and your Arc is connected to the ARC port on your Sony.

We’ll need more information, if that doesn’t resolve it. My two Apple TVs are running just fine, so it isn’t a software issue. Conversely, you could call Sonos Support to discuss it.

When you speak directly to the Support staff, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.

Oh, and make sure the program you’re testing with isn’t in stereo…not all of them are. Make sure you’re testing with a recent movie, or something like that. YouTube is somewhat famous (edit: perhaps I should say notorious) for converting everything from 5.1 uploads to stereo downloads, I assume to save bandwidth. 

It only plays stereo pcm. I had to change the output on the tv to PCM. If I didn’t i would not get any sound through apple tv. So now all o get on any channels through any hdmi ports is stereo pcm whether the channel plays 5.1 or not. 

Doesn’t make much sense. Please let us know the audio settings, all of them, on the Apple TV, and the TV itself. It would help to know how and where the Apple TV is plugged in on the TV set, as well as how and where the Sonos Arc is plugged in to the TV set. And, it would be helpful to know what you’re testing the signal throughput with. 

In general, the Arc will play whatever it is handed by the TV set. 

Yeah, a listing of settings for the ATV and Sonos, plus the source app and content would be helpful.