I was reading on another site about something called "Black Diamond Racing Cones". While researching this item I came across some interesting info about how equipment, and speakers, can vibrate, which sets up audible distortion. While I am having a hard time believing this in regard to amps and pre-amps, it made instant sense from a speaker perspective.
My 4 LSi15s are using carpet spikes, but they really are not that stable, especially side-to-side. While wondering how the Black Diamonds would help with the LSi15s I had an idea. Years ago I bought a 110 lb Olympic weight set that, like all home exercise equipment, sat unused in the garage. I went out, got the 25lb plates, and put them on top of each LSi15 (a cloth is between the speaker and plate).
This made them more stable and planted to the floor. The real surprise is that they sound better!! Clearer, more precise, more detailed. I am amazed. I made a sonic improvement without spending a ton of money.
The only issue is whether the 25lbs is putting any type of damaging stress on the speakers. And being in earthquake country I have to remove them when not in use.