The issue here is whether this counts as the production of copies and/or whether that production is fair use.

For example, CDs are digital. To play a CD that you own, the player is going to create a copy of the song in memory in order to decode it into an analog signal that can be played on speakers. Then it's going to discard that temporary copy, leaving the CD as the only permanent one. It seems pretty obvious that either that sort of temporary copy doesn't count or that it should be fair use.

But then how is it any different if the temporary copy is on your tablet instead of your CD player?