I live in a small room in a duplex, so as much as I love bass, I have to eliminate most of it. In terms of where I can put speakers, I can really only use 2 walls and plus I have 2 setups, a desktop one and a Home Theater one. I rearranged my room a few times, put up some blankets and even converted my 5.0.2 to a 3.0 at times. Generally when I use my subwoofer, I hear about 25% of its volume in my chair and my towers bass I can hear about 35% of its volume in my chair (My towers are always set at -10db bass). As I recently got done turning my 3.0 into a 5.0.2, I'm just thinking about downsizing a bit. I'm a little tempted just rearrange my room again and use only bookshelf's. I was thinking either my pair of Polk RTI6's or even my Realistic Minimus 7's.
Would an Open Baffle sub-woofer reduce output transmitted through walls since it won't pressurize the room? Maybe Tactile transducers mounted on your couch or listening Chair?
That's about the way I would go about it. Isolating your chair from the floor would negate much of sound transmission of the Tactile Transducers to others in your duplex.
If your getting complaints? This might be the best way to go about it. I could not ever fathom living in a duplex let alone an apartment again.
It really is amazing how far Bass frequency travels. Even though its output at the listening area is barely audible.
I wonder if you made a 6th order box with port tubes directed at your listening area so they provide output to your ears, but then cancel much of that output to the room. Kind of like your coupled between them. So you get to hear it, but then quickly diminishes its energy out side of the space you are sitting in.
Maybe that would work? so it's like you're sitting in between headphones and you use your regular sub-woofer with active noise cancellation software so that it takes care of whatever bass that is in your room. I don't think it's going to work very well for low frequencies but it's something you could try out in your spare time with some free software into microphones