I’m stunned to read this. Over the holidays, my family and I did the same comparison. Not including Tidal, mind you, but we did put Apple Music, Google Play Music and Spotify head-to-head-to-head for the free trial period offered by each service.
The result was the opposite of your findings. Notwithstanding library size (which Apple dominates), we found that overall sound quality was better with both Spotify and Google Play Music than it was with Apple Music.
Granted, we did not exactly go to audiophile extremes for the audition. All music was listened to via Sonos Play:1, Play:3 and a sub-$2,000 home theatre 5.1 system. No fancy amps or tubes.
But you would think, that if we found Apple Music inferior on a system like that, it would get absolutely killed on something higher-end like yours.
I was disappointed that Apple Music performed as poorly as it did, after all, we’re a fairly Apple-oriented family and it would have been more convenient to stay with that platform. But the specs for each service would seem to confirm why both Google and Spotify sounded better — they both stream at 320 kbps, whereas Apple streams at 256 kbps (at least so says The Verge’s estimates).
We can debate the value of AAC lossless vs MP3 lossy compression, but even when I listen to music locally on a variety of devices, 320 kbps MP3s are pretty hard to beat. Yes, 24-bit FLAC does sound better, but not by the same factor that 320 kbps MP3s sound better than 256k AAC, IMHO.
All of this has me seriously stumped as to how you could find Apple Music a better experience than the others. For us, it was worse on every sonic metric I could identify.