I have found a similar effect, but I would not call it "decoupling", but coupling. I have B&W 803d's with 4 two inch brass footers mounted to the base of the speakers, which sit mounted on 3" thick maple butcher blocks 18" diameter. These are mounted off the carpet by an additional three 3" diameter brass footers. The overall impact of this system is quite impressive. Not sure how these work, but I believe the footers and maple butcher blocks serve to channel unwanted cabinet vibrations into the the floor. The overall effect is considerably better imaging and dynamics.
A recent thread about speaker/floor isolation
OMG!! I recently read a forum thread here dealing with speaker isolation from the floor. I had a pair of 1-3/4" maple blocks laying around unused so I thought I would place them under my Legacy Audio Focus 20/20's on carpet. I can not believe the difference. I am in awe! The sound stage is improved, the bass articulation is unbelievable the speakers are now showing me what they can really do. Everything from low end to treble is greatly improved. Whoever started that thread, thank you. I am now enjoying my system so much more.