Hi:
I will make some assumptions and guesses here in an effort to help you find a solution.
First, "management" usually will not complain to a tenant unless someone complains first to management -- management is most likely the voice of angry neighbors who want you to keep your music out of their apartments.
Do you live in a steel-frame building with drywall walls, or is it a concrete structure with concrete walls? My guess is that you live in the former and that it's not just the front door -- the entire structure is passing music, and hopelessly so. The only solution for apartment dwellers with potent stereos is to live in older, concrete buildings. The floors, ceilings and walls are all made of concrete, and it is much harder for music to get through (they use concrete to protect ICBM silos from nuclear blasts for a reason).
As for the front door, if the building will permit you to modify it, adding a good insulating strip at the top and bottom to prevent air (and thus, to some extent, sound) from passing underneath and above it will help. Again assuming building permission, you could install a heftier door. It may be aesthetically unacceptable, but you could also install a heavy curtain (something with a material like rubber lining it) that pulls over the door from inside the apartment, which should knock off a few more decibels. One of the above contributors is absolutely correct, however, that it is the bass frequencies that cannot be controlled -- the only solution to low bass escaping is to live in a concrete building.
Of course, the ultimate solution is a house out in the country.
Good luck.
