@vinylvalet. @clearthinker is absolutely correct. Any movement of the speaker enclosure is distortion. This occurs mainly in the bass. Put your hand on the speaker while playing a bass heavy number. That vibration you feel is distortion. The floor to the speaker is analogous to the tonearm to the cartridge. The floor has to absorb the energy transmitted by the speaker without reflecting it back. Admittedly, some floors are better at this than others but, that is a floor problem not a speaker problem.
All Speakers producing bass have to be anchored to the floor. Any other approach is absurd. The OPM should take this into account and anchor his speakers to the floor. If the spikes are too short to make it down to the floor then you need longer ones. If you feel uncomfortable doing this yourself find someone that is not. I would gladly do it for you if you live in New England.