Cdc - ".....you're trying to get rid of vibrations in the CDP itself."
Couple of things to think about 1)even if you could couple the CDP AND provide a path for vibrations to pass from the CDP (drain, if you please) wouldn't the vibrations created by the CDP itself already have done its damage? Now, assuming that you would argue that the vibrations would build up at the resonance point involved in CDP, and that to provide a 'drain' you would reduce the damage caused by the resonance, wouldn't you then have to have a materiel which will allow the resonance to pass thru it or allow the resonance to disappate within it by changing the nergy of the vibrations to heat?.
Fow example think of the soft rubbery products. It is established that vibrations are reduced/eliminated by materiels that absorb them/i.e changing the energy to heat. If the materiel you use is not resonant at any frequency (and such materiel does not exist BTW, even pumice stone has a resonance point) then how would it ever absorb the energy by changing it to heat.
You say that sorbothane made the bass muddy and slow - perhaps, just perhaps, what you are hearing is the absence of the effect of undampened vibrations in the CDP, but you happen to enjoy (without knowing it) the minor ringing effect thay may be creating.
Just something to think about.........
Oh, for reference, in case you didn't figure it out, I'm in the absorbtion camp and think the 'drain' theories have more commercial benefit than sonic benefit.