Before spending a lot of cash try mounting the cdp over a bicycle inner tube with just enough air to keep it suspended. Isolate the rack with soft rubber like gum rubber. Also try gum rubber or sorbothane under the cdp. You want to stay away from any hard materials often sold as isolation devices.
Isolating CDP from weak wood floor
My CDP skips (alot) when my 25lb son dances on the wood floor in front of it (weak joists). I have a solid Manna rack and use MIB bearings under the CDP, but there is really no up/down isolation. I've also tried nothing, bubble wrap and some thick rubber/cork feet--no dice. I just looked at some Solid-Tech discs of silence, which seem like they might work-http://solid-tech.net/isolator.htm. Before I shell out the $$, I thought I'd see if anyone else has faced this problem. Thanks. D