I've got my cdm-7SE's with factory spikes sitting on 16"x16" cast stone column capitols inverted and resting on the floor. These things weigh approx. 50 lbs. each and are extremely dense. They made an incredible improvement in bass response and tautness. One of these days I plan to upgrade the spikes (if not the speakers). I got them from a nearby cast stone plant as rejects that were sitting in their inventory yard for $20 each.
What's supporting your speakers?
I've had a lot of luck with Rollerballs or variants thereof under my electronics, including, surprisingly enough, a Power Plant. Seems like, in my system, the speakers just disappear a little bit more everytime I hit on a really successful tweak. i have ETC spikes under my Martin Logans right now, but was wondering if anyone has found a really great speaker footer.