I moved to a new apartment complex going from the ground floor to the second floor of a 3 story building & was totally paranoid about the upstairs & downstairs neighbors complaining.
Anyway, for $125 & UPS shipping, you can buy a heavy duty isolation pad for your subwoofer which is kind of like a thick doormat that you put under the sub. It doesn't affect the sound your hearing in your place but does minimize the noise/vibrations. I use them for both my bedroom & living room sets (costt me around $300 something with shipping for 2) & so far, in the 2 months I've been here, I've had no complaints, so I assume its working. The place that sells these is called accoustical solutions.com here is the link to the pads http://www.acousticalsolutions.com/p...ation/pads.asp I recommend if you do buy one you get the heavy duty one as the other apparently isn't as effective.