apple tv 3 generation and pcm stereo

I’d be checking the Apple TV audio settings, followed by checking the TV’s audio settings. Sonos plays what it is handed by the TV, there aren’t any ‘settings’ in the Sonos app to change playback type. 

I’d also check both the Apple TV and the TV itself for updates. 

It’s important to remember, though, not all films are shot in Dolby Atmos, so the Apple TV will pass whatever it is told to. It depends on the film, so make sure you check the listing in Apple TV. 

​@Olivier Paea 

Regardless of the actual settings issue I recommend to upgrade your AppleTV device at least to an AppleTV 4k. So you will be able to play Dolby Atmos Audio if your TV supports eARC or you use an eARC audioextractor. So you can profit most from Sonos Arc Ultras advantages. With ATV 3 you are limited to Dolby Digital 5.1. 

Great suggestion by ​@Schlumpf . However, I wouldn’t purchase the current ATV4K as there are very strong indications that Apple with launch an upgraded ATV in September 2026 or the 3rd quarter. Speculation is that it has been delayed until the full public launch of Siri is ready which is scheduled Fall of 2026.

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