Improving a stone rack

Yes, I was, my first career. Lots of folks from the department went to Skaergaard. This was in the mid 70s when they were just unraveling the sedimentary features of the crystals inside the chamber. Crystal turbidities and the chemical differentiation / substitution inside the Felspars, olivine, and melt etc.. I was at the U of O where lots of this research was going on.

But the first gabbro complex I used to climb around on was the Duluth Gabbro Complex. You just never forget your first gabbro complex.

I was fascinated by peridotite. And then, of course, serpentine exposures around the world. So my countertops are all serpentinized peridotite now.

I share experiences with others, whereby adding granite slabs under components or (especially here!) speakers has had a significantly deleterious effect on sound quality. Harsh, bright, brittle sound. Just awful. 

Of course there are also known quality products where granite slabs / sheets have worked wonderfully. HRS incorporates granite in their platforms. Acora speakers (granite cabinets) sound awesome. I've got a friend with granite bases (sandwich design) for his Vandersteens - works great.

I think the most common theme for success is that damping needs to be applied over the full granite surface (at least 1 side). Iso Acoustics feet on 4 coroners isn't enough - I even tried that with my speakers and the granite slabs - no help. 

Herbie's sells (no idea of current availability) his "grungebuster" material in sheets cut your needed size, and I believe that's what my friend suggested for use in a sandwich with granite platforms. Seems reasonable to me! At least cover the top of each rack shelf, in your case. 

I'm looking to use a glass shelf rack, 5 shelves that sit in slots in the wood frame with a soft vinyl supporting the shelves. A Technics 1500c tt will sit on the top. If anything, what type of damping would work well on a budget? I was thinking of the stick on felt pads that you put on the bottom of chairs so they don't screech across the floor attached to the feet of the components. Too simple? How about an old tt mat cut into pieces?

Granite (sorry!)  I don't know how bad the rack is but it's probably not great. The turntable on top is probably the worst location, especially if you're on a suspended floor. Anyhow, try it all out first and worry about damping then. Otherwise you won't know if you've improved things. 

@ghdprentice 

I must correct myself- I think you’re correct that this stone comes from the Bushveldt Complex in South Africa- I just looked up the location in Google Maps!