Just for info...
When I bought my speakers I asked the dealer to throw in some insulating bases for spiked speakers, as I've got a wooden floor. I've tried the speakers (MA RS6s) both with spikes on the bases supplied, and without spikes on the rubberised feet fitted to the speaker.
The differences were surpisingly great - with spikes and stands the bass no longer rattled through the floor and is more pronounced. The sound is more homogenous through the tonal range, whereas without spikes the bass end was curiously detached from the rest of the sound. Most interestingly, it has also toned down the treble end slightly.
I can't remember the brand I'm afraid - not at home at the moment - or how much they would cost (certainly not very much), but they would be worth the money if I was to have paid for them.