If the floor is a wood joist suspended type you might want to put the speakers/spikes on a harder, more inert surface like granite or for a cheap fix some concrete flag-stones from home depot at about $5 per. I found the wood floor acted like a resonating board for the bass frequencies and found the concrete helped. (best results though were with the concrete spiked and the speakers on aurios, but that was getting elaborate.) Stay away from rubber based footers as they compounded the bass-boom tremendously. (at least in my case.) Good luck. Oh yeah and don't forget the wool carpet.
