Butcher Block under Zu druids

Has anybody experimented with wood or other materials under Zu speakers?
I had Omens and they sounded best with wood boards under the speakers on the supplied spikes. I'm on the 2nd floor, carpet and the boards just seemed to tighten the bass up a little, made them play cleaner. The Omens, and I believe the Druids, port out the bottom.
I have a big thick butcher block under my turntable to good effect, but since this is about plinthing speakers, why isn't this thread in the Speakers forum?