I have!!

I'm now using oak cones + ball bearings under my Ruarks.....both under the stands and between stand and speakers.

This evening i just put wider cones under the stands....+9 mil BBs.  I'm not totally sure its a happy combo as the larger balls raise the speakers up a little, which i didn't want to do.  Bass is up, however and some extra detail.  I'll have to give this one soem listening.