If your flooring is wood and you have large speakers some sort of treatment is in order. I did some impulse measurements on my SC-V's (305 lbs) and on my old IMF Monitor IV's (90 lbs)in my living room. Under the location of the speakers I had cross braced the floor and put four floor jacks on oak blocks under the location of each speaker from the floor bracing to the concrete in the crawl space. My floor was built to hold a grand piano and the joists are full 2x10's on 12" centers with plank underflooring and oak flooring. This is certainly stiffer than most recently built houses. However, the measured impulse response clearly changed for the better as we adjusted the floor jacks. My bet is that any decent sized speakers on wood floors need some sort of bracing or decoupling. I'm going to take redkiwi's suggestion and get some soapstone and see if I can measure any additional improvements
Granite Under Speakers Over A Wood Floor
I would Like to use something over my wood floor that would not scratch it like the spikes do. I remember seeing sonus farber speakers on granite blocks. Does anyone have any experience with this? How would this sound?