Ch-ch-changes

Time machines.
Everyone wants one, no one has one. If they had one though, maybe the best idea would be to go Back In Time you make sure it was never invented. Or forward in time to do it. I don’t know. It’s one of those circular logic deals that always make time machines in fiction so shitty. Go ahead and try and name one movie where time machines as a plot device didn’t make it suck.
But that’s neither here nor there.
I’m interested in hypotheticals instead.

If you could go back in time and give one piece of music to a person in the past, what would you give, and whom would you give it to?