i have carpeted suspended wood floor. it used to resonate from bass. you could hear it in other rooms easily. it was on the muddy side.
i live in an apartment building and you could hear it thud down to the first floor at 60dbish. felt for my neighbors.
after several experiments, the final solution is my towers naked-footed on a paver with a horsestall mat between it and floor. my subs are on substands on a paver.
i have taken measurements but im dumb when it comes to interpretation.
i will say that this really did a great job decoupling the speakers from the floor.
now, id have to be up to 75db+ to hear it outside my door.
im very thrilled with the results.
i got the idea from a guy with granite plinths. i didn't feel like spending granite money. and they're heavy as.....
different materials, densities, and thicknesses make a difference.
for instance, i started with hardwood boards under the speakers. better, but after a couple of weeks, i realized the wood was adding a tone in. mdf was better but a titch dull.
stock feet sucked. svs feet worked well but i knew i could achieve more.
some cork and sorbothane pads i tried smeared the mids and bottom highs. rubber was dull, etc.
i intend to try a sandtray i saw that supposedly does similar. saw another guy with his entire kit in sandtrays. his stand was essentially a custom sandtray for each component.
and recently, someone mentioned mdf and laminated security glass.
so, i think decoupling is a good idea for folks with suspended wood floor.
just ymwv.