We do agree on this point. We both recognize that air borne vibration can be a problem.No we don't....
I pointed out that:-
If air-borne sound pressure is a problem in the turntable playback system, then every increase in volume would of necessity degrade the sound.You said that was correct....
You then contradict yourself by writing:-
The result is it is quite impervious to the volume level in the room; even at 110 db the sound is still very relaxed.The two statements are logically incompatible.
No amount of plinth dampening will avoid the effects of air-borne sound waves on the vinyl, cartridge, stylus and tonearm.
The fact that you and many others can listen to vinyl played back at excessive volumes demonstrates conclusively that air-borne sound waves have no effects on the turntable system.