How is your apt. situated? By that I mean are you on the ground floor, 2nd floor, etc. Are you sandwiched between neighbors or do you have an end unit? What is the construction/composition of the walls, floor, and ceiling? Are they concrete or some other less dense material?
You may find that down-firing subs will cause more "boom" being transmitted to those below. One thing to consider is to see if your neighbors would allow you to listen to your system from within their abode. Then make system/setup changes and see how it sounds.
This may help you to mitigate any unwanted sounds from disturbing them and would surely show them that you are trying to be a good neighbor...
-RW-
You may find that down-firing subs will cause more "boom" being transmitted to those below. One thing to consider is to see if your neighbors would allow you to listen to your system from within their abode. Then make system/setup changes and see how it sounds.
This may help you to mitigate any unwanted sounds from disturbing them and would surely show them that you are trying to be a good neighbor...
-RW-