I am an amateur sound engineer. I often have choirs and singers that practice, and sometimes perform, to playback music. Often I use MP3 files with reasonable compression, as these are sometimes provided with performance licences of various musicals.
It's obvious that a very bad quality (read strong compression) sounds awful, but would a slight compression, which is not distracting by itself, (like e.g. from Spotify), make a difference for a solo or choir singer? The singers I work with mostly are by no means professionals, but I guess this does not matter for this question.
Specifically, I wonder whether the quality (by this I mean compression) of playback music does affect the ability of a singer to intonate correctly.