I couldn't tell the difference on my old setup (Monitor Audio silver 6 with Yamaha RN-602). Given TIDAL's limitations, I stuck with Spotify. Now I have a Naim Nova, everything sounds better so I was going to try TIDAL again. My speakers are producing a lot more detail than they were.
That was before I heard about lossless coming to Spotify. I don't think I'll bother now. Hi-Res doesn't concern me too much. I believe only 10% of TIDAL's library is Hi-Res (happy to be corrected) and I'm not into a lot of mainstream stuff or Rap/R 'n' B which is what TIDAL does best. Their library is missing too much for me to consider signing up.
I went back to Spotify from Amazon HD. I just had it with the clunky apps (yes plural) I have to use to just listen to music. The HEOS app only plays the high res music but is unworkable, doesn't show the Amazon playlists, predictive text is missing, works with an annoying and illogical queue system. The AMHD app plays the playlists and shows recommendations etc., has to use the Alexa HEOS skill to be able to play on my NR1200 but it doesn't play high res, frequently crashes and keeps on playing and then I have to start the Alexa app so the AMHD app realises it's still on the air. When Spotify announced its HiFi tier I immediately cancelled AMHD and went back.
Don't get me wrong, AMHD's sound quality is awesome, (yes, I do hear the difference even with my budget setup), but the stupid to and fro between apps was often rage inducing and that is not the point of listening to music. Listening to music should be a joyous occasion and not make you want to break stuff and the absolutely shitty user experience of AMHD was just doing that.
So I will be content with and bear the lesser sound quality for a few months until Spotify rolls out the HiFi tier and all will be good...