In a Past Life as a ID TT Owner, I had a 9 Stone in weight Granite Plinth.
Granite of a substantial weight not necessarily at 9 Stone is a 'young man's sport', managing it as a material, requires quite careful considerations.
Today I still use Granite in Sub Plinth Designs as a Tier in a assembly of materials, but this is static in the selected position and is not intended to be worked with. The design that is in use for my Power Amp's has a Granite piece in use that weighs approx' 56 Stone.
For the TT, when tinkering with adjustable feet, the devices shown in the Link will do a good job of taking weight and making the working with the Footers more simplified. The method extends favourably to all TT's with feet that are adjustable.
For the actual Footer used, the Audio Technica AT 616 might prove to be ideal.
In the world of TT's Supporting Structures such as a Plinth/ Plinth Chassis, changes have occurred in how a TT is designed. Designs are now in place that are no longer recognising Mass only as being of value. Especially when a Mass Material is with very poor intrinsic properties relating to a Damping Factor and Dissipation.



