Granite surface plate

I haven't tried the ball peen hammer test. I plan to use a thick maple butcher block next to the granite. The table will rest on three Stillpoint cones pointy side up.

The table, an original VPI Aries Extended,seems to really benefit from as much isolation and as solid surface as possible. Seems like every small change is audible.

I've been using 2" granite, layered with 3/4" Corian, separated by 1/8" felt, under my amps for a couple years. My VPI turntable is sitting on top of a cabinet I built(30 years ago), on 2" of granite, atop 1 1/2" of HDF, with Texas Instruments EMI/RFI Shield and 1/8" felt between. There is zero acoustic breakthrough or resonance, as cramped as my sound space is, regardless of listening levels. As Mr G mentioned: Don't hit your granite with a hammer, and it won't ring. I'm NOT going to worry about a resonant frequency of ONE Hz.

Jump on granite don't worry about the sound.

I second Roxy54 recommendation of Adona shelves. Been using them under my TTs for years.

The Adona shelf won't cost a fortune, and it's just a "set it and forget it" solution that avoids a lot of experimentation and looks good.