vibrapods or cones?

Kitch: Before I switched to the Neuance shelf (for the tube amp), I used the Pods under a Maple cutting board with the amp resting on the board on its stock feet. This helped to clear up the sound, maybe because I use a 6922 type input tube and they can be a little touchy. I did not try them directly under the amp due to the heat (hot chassis). I don't have the material, but have wondered what a thin sheet of Sorbothane (with holes for the pins) would sound like between the bottom of the tube base(s) and the tube socket(s). Pods under the Renaud Twins (when they were on light stands) increased the bass, but I have not tried them with the new heavy Target stands (which on their own with tack increased the bass quite a bit more than the previous combo). The Pods under my cheap power conditioners and sometimes under a heavy power cord (to isolate it from the shelf if it happens to rest on it) clears up the sound as well, though it's cheaper to suspend the PC's with cotton ribbon and it sounds just as good to me.

Why not use both? My favorite "sandwich": Component on top, Cones beneath component, Black Diamond (or your preferred shelf) beneath cones, Vibrapods below the shelf (pods are sitting on your rack). Tune by experimenting with various types of cones; also tune by moving the cones around 1" at a time. Farther apart for more detail, closer together for more warmth.

David- you want to talk cheap, I've got all my wires off the floor with bits of cardboard! Not that I hear any difference. But it's de rigeur.
I'm currently building a Foreplay pre-amp from Bottlehead (Electronic Tonalities). One of the big tweaks is to isolate the transformer from the chassis with rubber grommets. That requires a separate grounding scheme, however. Another is to cut a mirror image of the top plate out of keldamp to put underneath. I don't know about damping the tube pins although there must be some vibration inside them. Having installed tube sockets, I would say that there would be a better chance of isolating the sockets themselves as they are grounded in the wiring scheme and not by attachment as are RCA's and such.
I may try some more pods under the newly acquired Monster 2000.

I second Bob's point. For electronics, including cdp's, try cones under the component and isolation under the cones. The cones will "drain" vibration from the transformers or moving parts in the components and the isolation (vibrapods, pneumatic platforms) prevents vibration from the floor/rack from getting into to compoonent and signal path. With speakers, a rigid coupling to the floor is key. Spikes minimize the contact between the enclosure and the floor, reducing floor-borne vibration, and they prevent rocking or wobbling that can cause time smear from speakers sitting in the floor or on a compliant surface like sorbothane.

CJ of CJ's AudioVideo, my source for Vibrapods, has been trying to get me to try the sandwich thing with MDF. I was put off, though, because originally my flexi-rack had MDF and the system was unlistenable. The 1 1/2" thick maple shelves I use now are at least neutral. I suppose I'll have to donate, what, $150 to Caterham's used Lotus fund and get a Neuance shelf. What do you guys like for cones? Pierre Frey tried to sell me $125 set of his Mapleshade cones. As good as the speaker cables are, I don't know.