Talk with your neighbors, telling them you just got a new HT and you want to find out how loud you can play it without disturbing them. Then play a movie or music with a good amount of bass, and go down to their apt. and check out how loud it is. You can then calibrate your volume to what they can tolerate when they are home. Be sure to invite them over for pizza, beer and a movie. They will appreciate how considerate you are. My brother did this with his neighbors, and it worked out great for him. His neighbors wanted to do the same with him for their system!