Granite Slabs

I agree with goofyfoot.  Most granite shops will have leftover pieces from builds.

I built an isolation platform for my turntable.  The process was go to the granite shop, let them know what you are doing, they will show you what they have available.  The shop where I purchased mine charged about 10 for the piece if you want it cut they will do that most likely my guy charged 8 per cut,  granite comes in either 3cm or 2cm slabs.  They may charge a bit extra if you want the edges smoothed off.

after that I sandwiched closed cell foam between the granite and and a plywood base.  I installed spikes in the plywood.  Or sorbothane feet whatever suits you.

Ah, good to know! Now where to find some local granite shops around Indiana!

Chasing the wrong things it appears.

Draining the vibrations has proven to be the best "sounding" solution.

Stack Audio Auva units are much simpler to deploy and produce tighter bass and more presence into the room from your speakers.

I've tried all ideas above before Gaia's on my Wilsons for years. Gaia's try to isolate. The Auva's drain the vibrations. Day and night improvement. So glad Stack Audio came along.

Just ordered Auva SW's for my REL subs and anticipate improvement there as well.

Messing with granite and spikes and all of the ideas here w/o the math is expensive and not rewarding from my experiments. Check out the Stack Audio products. They really work.

Happy listening!!

I have a set set of Linkwitz Orion loudspeakers. When I approached the problem of isolating them I tried spikes without a good result. Then I found out that Siegfried Linkwitz himself recommended a slab of 1 in thick felt. FELT said I !!  But being very reasonably priced I bought the material and placed it under the speakers. Who would believe it !  It worked extremely well and is still there!

Not sure that would work with 215lb speakers and carpet?