Being an individual who has experienced TT's that are the same model or models with similarities in how they function mechanically, where a broad selection of Plinth Materials are used as follows:
Plywood Boards of different densities and bonding methods - Bamboo Board - Hardwood - Composite Resin - Stone - Metal Coated Wood. I was able to make discoveries of what I was preferring as the mechanical interface on a couple of different drive TT's.
At a later time, I was able to experience the same TT model - same tonearm design- same headshell part on different plinth materials. There were cartridge changes involved to extend the learning attained. It was this experience that underpinned my already made decision for a use of a particular Plinth material.
I have once been very familiar with how a variety of plinth materials produce a mechanical interface with a few TT types, and can only suggest very strongly that an individual can completely rewrite their own rules when having been demonstrated the effect of the mechanical interface on the end sound produced, as the different materials are demo'd and evaluated for their interface value.