Does Atmos work with other streaming apps (example Netflix), either on the TV connected to the AVR through HDMI ARC,
or using other devices like the Firestick connected to the AVR's HDMI ?
It wouldn't make sense if that specific AVR supports Atmos with other streaming apps such as Netflix but not with Tidal.
I own the Amazon 4K Fire Cube, works great. All the Apps, Tidal, Netflix, Prime, Disney+, etc that do deliver Atmos content all work perfectly.
Most important is your AVR supports Atmos.
My Cube setup is Ethernet in for content, HDMI out to AVR for video and sound, and the TV is eArc HDMI connected between TV and AVR.
A couple times I had to restart the cube, but that is really just a minor internet glitch.
I have listened to some Tidal Atmos vs physical disc of the same music and the physical disc is better.
Some times I have been disappointed by the Atmos experience, like when I watched The Mandolorian on Disney+, I was disappointed in the weak signal of the heights.
This all has to do with the bit streaming, from what I learned here at QQ.
As far as function goes, I never really have any problems and is an added good experience for home enjoyment.
One little tip, that has worked for me, is adjusting the DB's (volume) in all the speakers but even more so the heights.
Even though initial set up, Auddessy, pressure meter, distance, etc, all set perfectly, I have found that increasing the DB's in the heights to be beneficial, mainly because with everything equal Atmos is certainly an immersive experience, but I like to hear the sounds coming down at me more rather than less.
Hope that helps.