A recent thread about speaker/floor isolation

As far as I see it, falcon quest decoupled and oregonpapa coupled.

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.

Sometimes you can achieve better sound anchoring speakers, coupled to as one with the floor. I find it can depend on not only the floor, but the speaker as well. Coupling can cause reverberation and unwanted coloration. In which case decoupling your speakers might be the better option. Even with a solid floor.

Ive gone so far as to get into the crawl space under the floor to reinforce it with 2x6s L brackets and a whole lot of porch screws. Sound quality vastly improved.

I had a sub that would very slowly but surely skate out of position and it was upwards of 100 lbs. As tiny as the movement was that can take away from the over all sound and impact. If your one to squeeze every bit of sound out of something then absolutely this topic is something to look into and experiment with it pays off and there are often free alternatives. I really like outriggers, especially on those speakers with narrow footprints. 

I also have a HSU sub woofer mounted on two stages of brass footers, with a maple butcher block in between. The sub does not move as all the brass footers have machined needle points either to the maple butcher block or through the carpet to the plywood subfloor.

BTW, a good site that explains how these brass footers and maple blocks work is Mapleshade audio.

I'm a big fan of "floating" the speakers. I had Eden Sound make me two Terrastone plinths for my B&Ws. The sound is far superior to coupling with spikes.