Coupling or Decoupling speakers?

I have always coupled my loudspeakers to the listening room floor with cones/spikes and thought that is how it should be.  I recently stumbled on a discussion of the issue.  After reading a good bit I decided to decouple my Vandersteen Treo CT speakers using Herbie's Audio Lab Titanium Cone/Spike Decoupling Gliders.  So now, instead of having my speakers spiked into the concrete slab under my carpeted listening room, the cones and spike fit into the decoupling gliders and ride on the carpet.

I was assuming I would hear a difference with music containing bass, especially as my 2wq subwoofers sit right behind each speaker.  The unexpected outcome is that even music with virtually no bass sounds smoother/cleaner and more "real".  The frequency balance does not seem to have been altered, everything, and I mean everything I play is smoother and cleaner.  The soundspace is more open and the decay into the recesses is just a bit l o n g e r.

Please share your experience/ideas/opinions about what is happening with decoupling versus coupling speakers.