Thank you for your response. I will do some in-depth (no pun intended) testing of the bass performance with spikes on quarters. I just needed confirmation of my idea that, by adding a couple of massive slabs of granite, the bass-coupling to the floor would be diminished. I could always move the carper over to the speakers and put the slabs on the carpet, then the speakers with spikes on the slabs. Looks like I'll be shoving heavy boxes around again for a few days, hehe.
Thanks again.
Thanks again.