I’m not entirely into the audiophile stuff, but from personal experience, you can tell the difference, last thing I tried was when I switched from Spotify to Apple Music, where the later has “lossless” option (I think even Spotify has that) but the difference was clear between the two for a streaming service, Apple one is just more clear and alive, I even opened the same song and kept switching back and forth between the apps just to make sure I’m not imagining stuff. Was it because the lossless on apple is better than the lossless on Spotify? Or something else? I don’t know.
Doubt it. The problem is that you don't know the source of the audio. That is the key difference, and since streaming even if you pick the right album the "same" song might come from another because it "is the same".
If you see such a huge difference across all music the playback software have manipulated the audio.
Assuming you have high quality set on spotify (even in the mobile-streaming setting, if you didn't use wifi).
I have the same experience with Spotify vs Deezer. I think it's more likely that Spotify has somehow screwed up their encoding process than that I would hear the difference between high bitrate lossy and lossless compression. Spotify's volume normalization also somehow makes everything sound worse but it's easy to disable.
In my humble unscientific test, I did have both at the same volume level (didn’t check the EQ though as what other commenter said), I even tried different speakers incl my car’s, nothing fancy or extremely measured, just as an average consumer perspective.
Even though they’ve been talking about it for 2 years AFAIK Spotify still does not have a lossless offer. And lossy bitrate is adaptive and middling (especially if not using premium).
