From what I have read here, I would start with improved speaker stands. I am not one for flimsy stands (e.g., TonTrager/Harbeth) so suggest something strong, stiff, and damped.
I second the recommendation for Sound Anchors stands by @buellrider97 and I have successfully used them with several speakers. They are as solid as it gets, and internally damped with sand. They provide a stable base and the footprint is usually wider than the base of the speaker. They accommodate 3/8-inch threaded footers or anything else you want to use.
My speakers are bolted directly to the Sound Anchors stands (i.e., no worries about the speaker-stand interface material) although I believe I used a thin sheet of IsoDamp, a harder elastomer, between the speaker and stand (primarily to protect the speaker finish). The rigid connection between the speaker and stand results in the substantial weight of the stand providing mass loading for the speaker. Under the stands, I have used a variety of footers through the years including spikes (gave up on those), Herbies Giant Fat Gliders, damped springs (similar to Townshend), platinum silicone hemispherical elastomers and, most recently, back to Herbies on my carpeted concrete grade slab floor.
Audiophiles seem to write off the hemispherical platinum silicone footers but I found them to be quite good. They can be sized for the weight they are supporting and, being an elastomeric material, they respond similar to a three dimensional damped spring. The problems may be that they don't cost much, aren't shiny, and don't have a complicated engineering explanation for how they function. In my system, they just worked. Good luck.

