Yeah I know how Spotify works. What I mean is the end user has no idea where the source comes from, how it was mastered or ripped, or what Spotify's criteria is

Yeah I know how Spotify works. What I mean is the end user has no idea where the source comes from, how it was mastered or ripped, or what Spotify's criteria is for quality. It is opaque, and there have been examples of bad digital masters/rips used by Spotify. It seems all you can do is report bad tracks when you encounter them: https://community.spotify.com/t5/Social/Jitter-due-to-bad-CD-rips/td-p/287860 https://community.spotify.com/t5/Social/Jitter-due-to-bad-CD.... The OP even gave examples of classical tracks which have audible problems. None of this is an issue if you rip your own CDs or buy lossless from reputable sources in my experience. Spotify you're at the mercy of whatever crap Spotify has been given.