Coupling vs. Decoupling for Bass Response

My work system is in the hay loft of a converted 100 year old horse barn. The floor is wide pine planks over wood beams and shakes with just the footsteps of someone walking across it. Needless to say it does not help my bass response. I have my LaScalas in this room, which are not exactly known for low bass in the first place. They have a rather large footprint (I believe around 2X3 feet). Any suggestions of some simple (re: inexpensive) ways to get back some of my bass that the floor is eating up? I'm currently using three cones under each speaker, but I'm thinking coupling may be counter-productive. I'm guessing that I should be looking at a means of decoupling. Thanks in advance for any suggestions.

Marco