Hello. 
 

Maybe this can be useful for more people using Apple Music lossless via Airplay 2.
 

I listen to my music with Sound check >  ON - all the time, but I noticed that the sound from Apple Music is not so clear as the sound from Tidal integration in the Sonos app. By clear, I mean not so bright highs, not so defined lower frequencies, and also mids. 
 

Well, not anymore.
 

After applying in the Settings > Music > Sound check > Off
 

AND 
 

Settings > Music > Dolby Atmos > Off (if it was on Automatic, or On)

The sound will immediately pop-up, as it should. 
 

(The change of Dolby Atmos settings is important here, because turning Sound check On or Off will not change the setting immediately).
 

I was surprised how the change is audible on my basic speakers. 
 

My setup: 
 

iPad 2019
Ikea Bookshelf Symfonisk after Trueplay calibration in the stereo pair
 

Tested with several records - Abbey Road from The Beatles, Diana Ross, etc. All in Lossless, or Hi-Res Lossless. 
 

Now, there is an ongoing discussion about the transmission of the sound via Airplay from Apple Music to Sonos. Is it 24/44.1, or 16/44.1, or AAC only? 

I can’t tell, but it sounds good to me. 
 

Thanks for reading!