OP, get an ATMOS receiver in your chains with airplay 2. Then you can "throw" music to it from your source (Mac or PC), from iDevices, or directly push music through AppleTV to the Receiver.
Instead of trying to flow music playback through your television, you MAY want to listen to that music with TV off. So a receiver can plug in between AppleTV and TV:
AppleTV HDMI OUT into Receiver HDMI IN... Receiver HDMI OUT to TV HDMI IN.
This allows you to turn off the TV and enjoy music from AppleTV. In this mode, think of AppleTV like an old CD player or iPod. If it was either, you probably would not be trying to flow the music through a television. Instead, you would link straight to receiver/amplifier to listen to your music.
OR, if you get a Receiver with airplay 2, you can do as I do and choose it as a airplay target from a Mac to play directly from Mac to Receiver (no AppleTV involved).
Now, what I do NOT know about these suggestions is the ATMOS part. Based on a quick look around- but certainly not definitive- it appears that Airplay 2 limits ATMOS music options to Apple hardware. If true, this makes me think that first option involving AppleTV to Receiver seems like it
should work if Receiver is ATMOS capable. The
Apple website section on ATMOS music confirms this
WILL work.
The latter option of Mac or PC airplaying directly to Receiver may not be able to deliver ATMOS. I mostly listen to my own music collection (ripped from CDs) so everything is Stereo. Someone else who KNOWS about this topic should chime in here. My guess is that this will NOT work unless you perhaps directly attach a Mac (with HDMI) to the Receiver via HDMI.
In your concept, I would always see the TV insertion as weakest link, as TV outputs are generally focused on audio associated with watching things on that TV. The optical jack on most TVs is notorious for chopping anything more than stereo fed to the TV down to stereo out. I'd definitely try to dodge any optical-based setup too. That standard is fading fast unless one can be happy within its limitations: 5.1 DD at best.
What you likely need is to work through HDMI as it is
THE way to shift ATMOS from one device to another. We know AppleTV is capable, so getting an ATMOS receiver as the next link in the chain seems most likely to deliver what you want. TV then is last link in the chain only if you need to see something on the screen. Else, you can turn it off when enjoying only music.
