I'm in a townhouse-style apartment: Only one common wall with another neighbor, no neighbors above or below me. In the four years I've lived there, I've never had any complaints. Of course, we don't really acknowledge each other's presence, either, so I can't say for sure how much I've annoyed him. On the other hand, he's an older guy and that leads me to believe he might not hesitate to complain if his peace and quiet is disturbed.
I recently upgraded(? - the jury's still out...) my sub to a HSU STF-2, and there's no question that it has greater extension than my EP175. This concerns me a little, because I definitely don't want to be "that annoying neighbor". But I've taken a few steps to make his life a little easier:
1. The M22s are well away from the adjoining wall - maybe 2-3 feet. The stands are filled with sand to minimize vibration.
2. The HSU is very close to my listening position (< 2 feet). The trade off is that it's much easier to localize the sub, but the upside is that the level can be reduced.
3. I definitely pick and choose my times to play movies with louder passages. If I throw in something like Gladiator or The Empire Strikes Back, I want the full experience. But I might wait until later in the evening when he's almost certainly in bed (the bedrooms in these units are upstairs and horizontally distanced from the living rooms), or I might wait until a Saturday afternoon when he's out of the house.
I've also tried feeling the walls when I'm listening to music or a movie at what I'd describe as a reasonable listening level. There's very little vibration, so that makes me feel a little better. Finally, a decent way to check things is to use your SPL meter. My feeling is that anything too far north of 70db is probably unfair to your neighbors.
Hope this helps.
