Granite under your amp???

It's probably not really something you want on a rack, the granite will weigh upwards of 200+ pounds. Difference in sound = slight at best. Looks very cool. The best/cheapest way to get a nice one of these is to buy what's called a Machinist's surface plate from one of the online tool vendors. For about $50 you can have a 2-3" thick, polished slab in 12x18 or 18x24" size, slightly more for the larger one. As a bonus, it's a precision flat surface within very close tolerances, so if you need to true up some straightedges or something you are all set. ;-) I've thought of getting a couple, but they are mostly just eyecandy, and at 250lbs, heavy to move around.

-Ed

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