Vibration Control

yes, Galen Carol Audio is better than most other dealers in that he gives more info about tweaks, tubes, etc. The other person that gives such info is David Magnan of Magnan Cables. Visit his website too sometimes.

Re. granite - yes, it does have its own resonant frequency & if used incorrectly it will ring. Ditto for marble. However, to say that granite should not be used is quite wrong!
One needs to understand the characteristics of granite (or any other damping material) before it. You'll see that most damping materials today are made from differential materials i.e. 2 or more materials put together to create a solution. For example the very popular HRS damping sheets, the Cera-pucks, etc.
So, if you damp granite with some cork, granite will not ring & it'll provide you w/ some superb damping (that would be superceded by only slate).
FWIW.