Granite under wood for better isolation?

Where do you live? Under the El? How much rumble can there be?

2 inch thick maple ought to do it by itself without the granite. But if you just need a place to store the granite - well, underneath the maple would work.

I have a similar setup with a 1" granite base. I used a 1" MDF board and sandwiched a 1/4" cork it has isolated all floor noise to zero and ever getting back to my turntable. MDF is allot cheaper and more effective.

Go down to your local home depot and pay $1.00 for a scrape piece. They will even cut it to size.

Enjoy Music!

I have had good results using different types of isolation materials in combination. In my system, I use various combinations of maple, carbon fiber, sand, and viscoelastic materials, sometimes combining as many as three different materials under the same component. I have found that combining materials offers a significant improvement over each material used individually. I have not, however, experimented with granite, so I cannot comment on the likely results of combining it with maple. But I think your experiment is worthwhile. Good luck.