Fantastic discussion and information, particularly in the @phoenixengr link. Gotta get some me Corian! Bill, do you think slate is approximately the same as granite in terms of stiffness, resonance, self-damped characteristics, etc? I like the look of slate better than that of granite---slate looks like Hot Rod Black paint jobs ;-) .
In addition to the 3M tape mentioned in the linked diyaudio forum thread, ASC makes a constrained layer damping product they named Wall Damp. It was designed to be installed between two layers of sheet rock, and I have heard the results when that has been done (in Audiogon member folkfreak’s room). Very, very effective.
I talked to ASC about using Wall Damp between a layer of relatively-stiff material (I named slate or granite) and Baltic Birch ply, and he said it is more effective when both layers are less stiff. He said constrained layer damping products work by absorbing vibration and converting it into heat. The less a material vibrates, the less effective is CLD. MDF is far less stiff than 13-ply Baltic Birch, so I assume it is the better choice for mating with Corian or Panzerholz.