Get a complaint letter sent to every apartment? But it only works whenever your building isn't that big. Or spread the 'word of annoyment'. Otherwise, good luck and invest in a nice pair of headphones..
If there are 8 floors, that must mean there are a lot of tenants, which means op will probably find out real soon where they are, because a lot of other people are probably pissed too.
Borrow a friends dog and get it to bark all night; loud music that vibrates the floor. I'm just taking things from my life in apartments at this point.
Have the painting crew play tejano on the landing while drunkenly sledding down the stairway on empty refrigerator boxes at 3 in the morning. It annoyed me enough.