2020 update : JC Verdier La Platine

I am spending a Proportion of my time visiting a Thread that has a certain appeal, as it shares an interest where mechanical interfaces are being investigated / work with on a TT.

Reports on where value has been found is where I shlow my interest.

How the TT is mounted is a mechanical interface, when this is considered, is when the 'X' Factor can become more than the sum of parts, a new and unimagined tidiness to the End Sound manifests.

Methods used for mounting a TT, when addressed, can substantially extend the good impressions of other work carried out.  Alternatively the mounting method is a good practice, resulting in a much tidier and gathered End Sound. 

I have no dog in the fight, but experiences compel me to make the suggestion about considering how the TT is supported.

Considering costs $00.00, but what can be learned will be off great value. It is worth mentioning in recent years very established Vinyl users on the Gon, have had profound experiences as a result of making simple changes to methods used for mounting a TT. 

A basic description of a basic structure design for a Timber Cabinet in use as a Sub Supporting structure for a TT. Where the Stylus is the concern when in contact with LP groove modulus, Can be stated, the structure is more akin to a Drum Skin. Both ambient energy transferal and the TT in use energy transferal are more than capable of generating amplitude in the cabinets structure that will be a negative influence on the Stylus whilst extracting modulus data being sent to become End Sound. 

For heavy, non-suspended TTs, I like to use this kind of air-suspended optical tables!
 

https://www.techmfg.com/products/cleantopopticaltopsandsupports/opticaltopsupportsystems/microg

For heavy, non-suspended TTs, I like to use this kind of air-suspended optical tables!
 

@thekong 

That may be ok if you have structural floor problems but it is suboptimal.

You cannot measure the groove accurately if the TT is bouncing around on an airbag.

As an experiment, stand on top of a bed with an innerspring mattress under your feet and try to measure accurately the height of the ceiling with a tape measure in your hand. You'll never get the same reading twice.

Let's agree that there is not a static surface anywhere on planet earth. Everything is vibrating / moving against everything else. Therefore there is a flaw with @dover 's airbag / mattress analogy. The purpose of the optical table or any such devices is to counteract the vibration from the floor surface with its own vibration. The net result is  less vibration. It cannot be zero vibration, just less. The lesser vibration  will allow instruments sitting on top of it to perform highly accurate measurements. The accuracy level required and achieved is many order of magnitude greater than the pitiful toys we play with called the turntable. we can debate the efficacy of the particular optical table in question. But the principle behind these devices is sound, no?

Not to belabor the point, but a more accurate analogy : the mattress is analogous to the floor. The optical table rest on the mattress. With the oprical table functioning properly, the person on top of  the table should be able to make a more accurate measurement of the ceiling height.