Downsides to Airplay from apple TV 4K to Sonos Arc Ultra?

I’m not sure how you are attempting to have your Apple TV connected to the projector by HDMI but still Airplay audio? I’m not sure that can happen concurrently? The HDMI cable from the Apple TV isn’t selective in what it sends - it will send both the picture and sound together to the projector. 

I can’t see how you’ve any choice but to connect the Apple TV to the projector, with the projector set to passthrough (so the Dolby Atmos isn’t impacted by any projector processing) and run HDMI from the projector to the Arc Ultra. 

Edit: unless you’re Airplaying from the projector if it supports it? In which case, the sound will be fine but only fine. You really don’t need an Arc Ultra if all you’re getting is stereo…

Edit 2: you could look to send the audio from the Apple TV to the Arc Ultra by Bluetooth (as you would for Airpods).

That was essentially my question - would I sacrifice the sound quality of the Arc Ultra if it only outputs stereo? your reply seems to indicate that i would :)

Note that the question is hypothetical. since I only have the projector for the moment. Fortunately it seems like it will be possible to use the projector in the manner you’re suggesting, as it has 2 HDMI ports, one of them being eARC:

I guess I'm going to have to get creative to avoid a rat's nest in my living room ^^ thanks for the advice. 

​@nassar I just posted two edits in my original post: one of which was you could send the sound from the Apple TV to the Arc Ultra by Bluetooth, as you would to AirPods for example. (AirPods get Dolby Atmos from Apple devices by Bluetooth - don’t know if the Arc Ultra would output Dolby Atmos that way though, I’m afraid. Someone else may know.)

The other edit was about Airplaying from the projector to the Arc Ultra.

You can stream via Airplay from the Apple TV to the Arc (Ultra), Bluetooth would actually be a worse option, but in both cases you will only hear Stereo.

For me it would be a no-go, if I buy an expensive soundbar I want multichannel audio of course and it’s also a difference by day and night. The dedicated center channel in multichannel track alone brings so much advantage over just stereo.

Thanks to both of you for your replies :)

​@Outburst out of curiosity, do you think i’d feel a marked difference between stereo and dolby atmos when streaming music? i.e. would it be worth me prioritizing apple music over spotify in pure music streaming scenarios just for the sake of benefiting from atmos? 

I only have tested Atmos music a bit and yes, it’s very different to normal stereo mixes but if you like it better or not you can only test. While I found some nice Atmos mixes I definitely prefer a normal stereo mix over Atmos and I also prefer my two standalone speakers wired to a Sonos Amp over the Arc Ultra for music playback. Please note though that I have tested Atmos only in a full Sonos Atmos setup with Arc Ultra and two Era 300 but the it still stands that Atmos mixes are much different.

I think when it comes to Atmos vs. Stereo music you’ll just have to test it out and compare it. Just get Apple Music for a month and test it out.

Understood. I don't expect to expand the setup beyond the Arc Ultra, since it's hard enough getting audio equipment into the house without trying to sell my (amazing) girlfriend on an amp/receiver and additional speakers hahaha. 

The good thing is that once we have the sound bar, we'll be able to test both configurations, both for music and with the projector. once that’s done we’ll figure out how to do the cable runs if they end up being necessary (who knows - maybe we won't be able to tell a difference between stereo and atmos, or maybe the media that the projector streams won't even be atmos mixed).

Thanks again for the patience and helpful advice. 

You keep mentioning Atmos but please note that you also would not be able to play any 5.1 or 7.1 content if you use Airplay or Bluetooth and I think that is actually the bigger issue. There is indeed not that much Atmos material (but it’s getting more and more) but most, if not all, content has at least a 5.1 track these days and that is far superior over a plan stereo track in my opinion. 

Yes indeed - based on this thread, I'm now making the assumption that if i want to play anything aside from stereo from my apple TV/projector, it would have to be via HDMI. 

If you want to make the most of an investment in an Arc Ultra, ten yes. Dolby Atmos music is often night and day vs stereo, as ​@Outburst mentioned. There are some terrible mixes/producers out there but when they get it right it can be incredible. And then of course your Apple TV/projector will likely be playing movies or latest streaming series, so Dolby Atmos will be essential for those. 

Sorry to bring this back from the dead, but I just saw this news: https://9to5mac.com/2025/05/13/tvos-18-5-just-gave-your-apple-tv-4k-a-new-feature-for-dolby-atmos/

Maybe tvOS now actually supports airplay playback for atmos properly? sounds kind of exciting! 

You could try it, but maybe Sonos needs to support this too?

I wouldn't think quite yet, Sonos hasn't said in their update notes that they've integrated the latest Apple SDK yet. I’d hope soon, but i dont know where it is in their priority list of things that need to be implemented. 

Sonos, please take note: https://professionalsupport.dolby.com/s/article/Dolby-Atmos-and-Dolby-Audio-over-AirPlay-Application-Developer-Guide?language=en_US