You could file suit to abate a private nuisance. The problem with the lawsuit is that it will involve significant time and expense. Do other tenants have a problem with this neighbor? I'm surprised that the landlord has not been more responsive. The City of San Diego does have an ordinance that deals with noise abatement and there is a phone number to call in the govenment pages of the telephone directory to register a complaint. Other local municipalities also have similar ordinances. Another alternative would be to request the offending residents to attend a community mediation, where the issues can be discussed in the presence of a mediator, who may be able to assist the parties in reaching agreements that may solve or at least mitigate the problem.
You could also try to get a restraining order to limit the times the neighbor could play their music.
Get yourself a good decibel meter and record the levels and details whenever it happens.