Maple or Granite

Since you already have the platforms, consider trying both platforms under the TT, with five heavy springs between the two slabs (granite on top, maple underneath.) On-line at McMaster-Carr, P/N 96485K125. I think you'll be pleasantly surprised.

Heavy springs between two platforms is a variation of the Promethean platform. Ideally the TT suspension would be unsprung so as to improve coupling between the TT and the top platform layer. The spring layer below decouples from earth, and the platform and plinth above couples the motor/stylus to a more substantial & absorbent mass than is available in the stock TT chassis/plinth.

I heard improvement with this system using both sprung & unsprung TTs. One could experiment by trying the Voyd on its spring suspension & also with its suspension clamped down. I tried both set-ups with my VPI TNT and preferred rigid coupling inside the VPI suspension towers in lieu of the stock sorbethane.

I found that although a sandbox is a good dump for vibration from a TT, a sandbox does pass vibration from earth to the TT and from the rack underneath acting as an antennae for acoustic waves propagated by the speakers. So I elevated my sandbox on springs with a maple layer below the springs. Even with a very solid rack on a cement floor this system improves coherance. Others I know have heard similar improvements with Raven and VPI Scout TTs.

In any event for $35 it's an easy experiment.

Try the $7 springs, then the $8 Cones, then the $100 Stillpoints.