Fwiw, I use a Dspeaker Anti Node in my home theater. It works well removing unwanted peaks, nodes, etc. After running the correction program the sub is more controlled and appropriate, not as 'loud'. I don't enjoy hyped bass.
While setting up the program you can hear nodes in the room being excited before being corrected, nasty business!
I don't know if this would translate to your neighbors hearing less bass, just wanted to mention the technology and opportunity.