It’s a good mix. Anyone else finding the levels very low on Tidal (via Apple TV)?
Yes. Everybody else.
It is a well known 'feature' in TIDAL that the Atmos tracks are playing at a significantly lower volume level than the stereo tracks or other 'normal' sources.
Some of us have reported this to Tidal support but the answer has been always the same: "Trank you, we will inform the technical group about this..." or "We are addressing it, but It is a Dolby problem, not a Tidal problem..."
The culprit is a parameter called "DialNorm" (Dialog Normalization) that Dolby included with Dolby Digital when it was chosen as the codec for digital TV transmission in the US.
It was designed to "evaluate" the average dialog level of the Movie, or the TV show, with respect to the maximum level on the movie (explosions and the like). This way, when a commercial is broadcasted, the global volume should be reduced (the amount given by the parameter dialnorm), because the average dialog level in commercials is higher than in a normal movie.
The parameter may be calculated using a special process (average dialog level over the whole program) or may be set by the sound engineer crafting the final Atmos track.
What's the meaning of "average dialog level" for music?
None at all.
Music tracks should not use DialNorm parameter (or set it to -31dB which means no reduction volume level). The volume level for a music track should be what is set by the mixing/mastering engineer, without modification. But many musical producers use the parameter DialNorm and set it with more or less "random" or incoherent values. Why? ...
All TIDAL Atmos tracks (DD+ with JOC) use to have different values of DialNorm, that result in none to -12dB or -15dB volume reduction for playing. The parameter value can be seen in the file with the MediaInfo tool, selecting Debug/Advanced Mode.
The effect of DialNorm cannot be "disabled" in players/decoders/AVRs.
EDITED: It looks it would be possible on some AVRs. See Listening to in Dolby Atmos Streaming, via Tidal/Apple/Amazon
Apple Music, with its own flavor of encoder/decoder for Dolby Atmos, (and using Dolby MAT), may have different results and it seems the difference in volume level is less than with Tidal.