Static...in Australia, if you play music as a 'atmosphere' in your shop, it is determined a 'public' broadcast and royalties are required.
It is deemed not the same as playing it in your own home and others coincidentally hear it.
What a DJ is doing, by 'mixing' or creating compilations is quite possibly a serious issue.
What if some 'bible-totin' religious band's music managed to be on the same compilation as a death-metal satanic style?
Yes, I know....quite fanciful, but a serious transgression of morals and ideology of both groups.
Not only would/could you be sued for breach of copyright, but also defamation or diminution of reputation and potential future lost earnings.
Giving away, and/or selling a compilation is a clear breach of copyright, not covered by 'fair-use'.
Creating them for private playing can be 'fair-use'....