XLR question for bass

1. Moving the subs around will offer the best solution, assuming that there is no veto vote.
2. A DSP is another solution with or without #1
3. The isolators can work.
4. The XLRs are about the last thing that has a chance of being noticed.

So I would stop before #4, and not start with #4
#3 can be cheap and easy.
#1 is also cheap and easy.

Like ghdprentice said:

"Your best bet is speaker placement. Moving the speakers back and forth from the wall, and your listening position"

You may be sitting in a null point where the bass is cancelling out.  Have you tried moving your listening position?  In my room I have two listening spots.  The first is in the sweet spot - almost equilateral triangle.  Bass is good - tight, punchy and faster.  The second is about 4 feet further back at my drawing table.  Still sounds good but the bass is just a little overbearing on some tracks.  Actually works out pretty well because I usually sit at my drawing table at night and listen while I work.  The additional bass oomph works well at lower nighttime volumes.  Like a built in loudness button!

Pulling the speakers any farther out into the room might lean them out a bit more.  But it might change the bass nodes also.  You have to experiment with positioning first - both the speakers and your seat.  Or, maybe you've done that already?  

You need room treatments. You have a bunch of hard surfaces and 90 degree angles. More gadgets and speaker placement aren’t going to cure bass frequencies bouncing around the room.   An area rug, a couple heavy blankets, a decorative gobo panel or two, some decorative acoustic wall treatments (I use Acoustimac and ATSAcoutics in my home and studio) even just one or two bass traps will make a world of difference. That room is screaming for something to knock down those sound waves.   The best system in the world would sound bad in that space.  Don’t invest another dime in gadgets or waste your time moving speakers until you put some diffusion in that room.

It will probably not be easy, but looking at the photo of the room, I guess that the intervention of an acoustician will be necessary. Good luck