Good Morning!

Talk to the landlord. She can say that several people on the floor have complained. Or that there have been complaints.

If you run into him in the hall, tell him. He will probably be embarrassed in real life. Invite him over. Become buddies.

Or leave a note.

Invest in heavy tapestries for over the walls and rugs to help absorb sound. Also, white noise machines/apps/CDs.

Or, beat him to the punch and crank up soothing/inspiring classical music before he comes home so he has to listen to that. When you turn it off, it will be midnight and he’s probably not going to crank heavy rock after The Best of Beethoven.

Good Luck!