Speaker shock absorbers

newbee - I agree with that statement. It appears that you are in sync with the effect that I was trying to control. It had occurred to me that some of what I was feeling was due to the sound wave without interaction with the floor. I do not necessarily want to eliminate that effect. My only goal is to get rid of any transmission that is not airborne so to speak. As to sound traps in the room, I have several in place, the goal of which was to reduce the liveliness of the room which, without the sound traps ends up reinforcing the high frequencies - those have worked well for that purpose.

I have had great success with "Unhappy Balls". They work in this application to 1) absorb vibration 2) do so while remaining stiff. Halve the large size (1-1/2" Diameter) ones for a secure fit. http://scientificsonline.com/product.asp_Q_pn_E_3039129

I do not necessarily want to eliminate that effect. My only goal is to get rid of any transmission that is not airborne so to speak.

Heavy underlay with heavy carpet on top is by far your best bet. Try to dampen the entire surface rather than just the interface beneath the speakers.

If you have to go upscale, as I did, you might like to know that Herbie's Grounding Bases worked very well under my spiked floorstanders... at a price.

Why aren't you using spikes? Do you imagine most speaker manufacturers include them for decoration?
Spikes actually 'decouple' the speakers from the low-frequency structure-bourne feedback able to be carried in most timber-framed floors. These large-wavelength low frequencies are unable to 'cross-over' the tiny contact points of the spikes. Any rubber or foam you introduce between the floor and the speakers will simply ' bounce' with the feed-back induced movement of the floor and if anyone out there considers 'moving' speakers to be a good thing, they may not be the best people to listen to?