Rectifier Clip

[black sugar]

Not a lot of easy fixes for that since you are talking about notes below 150hz. I would suggest getting the cab off the floor using a mopad or something similar. This might help alot since it sounds like your problem mostly has to do with sympathetic vibrations. Then start adding 703 panels until you're happy (or happier).

One of these might help to de-couple the cab from the floor for starters:

http://www.auralex.com/sound_isolation_gramma/sound_isolation_gramma.asp