Great, your description is a BIG help. Yes, your room, particularly with 15" subs, can probably use a ton of damping. Have at it. You could make the speaker end almost totally dead and it wouldn't be a problem. As it is, I can't imagine that the speakers are not overpowering the room. Thankfully the walls, floor and ceiling are sturdy, so you can probably get a quite nice result deadening one end.
Here's very important advice from someone married almost 40-years, et the wife get the silk. ;-)
Dave
Here's very important advice from someone married almost 40-years, et the wife get the silk. ;-)
Dave