How do iso. cones work and what are the benefits?

Try this little reading, it may help:
http://www.topdogaudio.com/pages.cfm?ID=14

Easier than readin all that. Have her contact me and I'll have my wife write her back. She couldn't believe it (and neither could I) when I put the BD Racing cones under the cd player the very first time. I still don't "get it" and think it's voodoo BUT we did notice another large difference once I put the large DH cones under he pre-amp.

The references above are very good. I also agree wtih Imin2u that, in the end, all that matters is whether it sounds better to you. My experience has been that these cones create a very positive lift (no pun intended) with the cd player and a noticeable, but far less dramatic, improvement with the preamp. I've also noticed very significant gains with metal cones under my Thiel 6CS speakers -- these gains were even more dramatic than what I experienced with isolation cones used with the cd player. On the other hand, cones or spikes with my current speakers make very litte difference (they weigh a few hundred pounds each, so that could be why). Try it, you'll like it ;-) If you don't, be sure you're able to return the cones. There is no burn-in period. You'll know right away.

By the way, I'm very pleased with my Stillpoints Universal Resonance Dampers -- I use the base and the "cone".

What about Darumas under the CDP, rather than cones? And 5lb or so of lead shot (or other weight) on top of it?

In short, points, spikes, and cones are meant to create a one-way ticket to expedite the exit or transfer of any air-borne vibrations captured and resonance within the component, speaker, or rack to whatever lies beneath it. Eventually, the vibrations are transferred to the sub-flooring system, the foundation, and finally ground. But we are talking microscopic vibrations not jack-hammer or 200mph racing type of vibrations.

By one-way ticket, meaning these microscopic vibrations may freely exit but not enter.

And brass is supposedly the best metal to accommodate this transfer process.

I received decent improvements when I installed Star Sound's smaller Audio Points underneath each of my components.

Again I received decent improvements when I installed the largest Audio Points on my speakers and custom rack.

But then after mechanical break-in of the larger Audio Points under the speakers and rack, the sonic improvements were nothing short of phenomenal.

One of the best upgrades I've experienced to date.

BTW, cones, points, and spikes are by nature not meant to isolate vibrations, but are hopefully designed to transfer the vibrations away from whatever sits atop of them.

And like anything else, one should never assume all cones, spikes, or points are created equal.

-IMO