When a file can be downloaded, it is imho not illegal to have data somewhere where it can be downloaded from. It is illegal to download when you do not have the right.

When You have music available, that you bought, and you use the net to download it somewhere else, to listen to, I do expect that to be fair use.

When somebody is charged with illegal actions, it must be proven to be illegal. Listening to your music on a different location can hardly be called illegal. The proof of illegality is in your own mouth and/or for organisations to prove..