It sounds like the feet on your speakers are too fat to cut through your thick carpet and bight into the wood floor underneath. If that's the case, thin spikes should solve the problem. If you call The Cable Company and tell them what you need, they should have it right in stock.
Anything you can put between spikes and carpet?
I've been playing around with my speaker positioning and a recurring issue that I've never quite been able to satisfactorily resolve came up again. While my speakers - Verity Fidelios - have pretty long adjustable spikes on heavy brass footers, I never feel like they're making especially good contact with the subfloor under the carpet and pad. I think I could possibly tighten up my bass response with a more solid contact. Is there anything that I could put the speakers on that would give them a more solid coupling for bass purposes? I was thinking of some heavy MDF squares, or even Corian, but then of course the board is not coupled to the floor. Any thoughts?