I don't want to upset ANYONE, but I can tell all of you out there who are reasonably handy with tools how to build an excellent device for isolation. Its theory runs contrary to Tom's sincere advice, but, in my experience it works well. It works at the root level, on the principal that the sum of the mass of the device, is greater than the amount of energy that one can transfer into it. The energy, within, say a preamp, converts from Kinetic to Potential energy. There is no device that I am aware of which can transfer 100% as someone pointed out, but this will improve the sound of preamps, cd players, and amps on several levels. The lead within it acts to shield RFI, which helps too. It contains lead shot, (not good healthwise) and a sorbothane like material, which when melted gives off noxious fumes, so making it is a bit of an issue, but overall simple. Also, hardwood, a couple of pieces of plywood, and finally teflon feet If you would like to know how to: just email me I am glad to share. It does really work. It is also about 80 to 100#'s, and very unweildy. This is meant to be helpful, and not in any way disparaging of anyone else's thoughts or ideas.
Thanks and good listening.
Larry R. Staples