Granite under your amp???

I was thinking more like 1" thick. Dimenesions would be no bigger than 17 1/2 x 19 1/2, I can't imagine this coming anywhere near 200 lbs.

A piece that size in 1 1/4" thickness weighs 36lb. I use them for shelves in a sand filled Lovan Sovereign and they work very well.

Gene

Please keep in mind that granite does not have very good tensile strength and needs to be supported by something that has the ability to carry the weight and not bend. I was carrying a piece the other day by the edge and half of it just broke off and fell. Consider what would have happened if it was being used to support an amp. Ouch!

Does somewhere like Home Depot carry these? How much would I expect to pay?

What exactly does it perform? (Reducing vibration...?)

As for support, I would place it on one of my shelves on my Sanus stand.

Surface plates (the cheap ones I mentioned) dont' come as thin as 1", 2-3" is the norm. Shipping weight on the 18x24x3 is 200-250lbs IIRC. 17x19 (weird size, btw...not going to find something like that off the shelf) x 1 is still going to be 50+ lbs., at least. It's tough to estimate the density of stone until you work with it in person. For the surface plates I mentioned, $45-135.
-Ed