Source of Fremer's "1 arc second" claim?

Yoyo, It seems you are insisting there must have been a difference that would be clearly evident to keen audiophile ears, when MF had to listen to the Wilson Benesch TT without the ThorLabs base.  How can you possibly know that unless you were at his home, in his room, at the right times?  A poured concrete basement floor is very inert without help from an air suspended base between it and a TT.

@lewm. A poured concrete floor isn't that inert at all - ask laboratories that use electron microscopes. In any event, isolation bases are there to isolate from airborne vibrations as well as those coming through the floor. And a pair of XVX's will produce both.

All of the EMs at the National Institutes of Health are in the basements of the various buildings that house them. The one in our building was not further stabilized by any sort of air suspension. Yet it was stable enough to permit visualization of subviral particles. Three of my friends collaborated to identify Hepatitis A virus on that ’scope. I will grant you that the building was built during the Cold War and designed to sustain an atomic blast.  The walls throughout the 3 story building were 2 to 3 feet thick.  So probably the basement floor was sitting on many feet of poured concrete. Nevertheless, I take issue with the notion that even a typical poured concrete basement floor "isn’t that inert at all".  We are talking about playing a record, not running an EM lab. And there are no train or truck routes through most neighborhoods we affluent audiophiles inhabit.

@yoyoyaya @lewm As a fellow EMer, it is important to put things into perspective. That's the same issue as with the 1 arc second claim. For instance the SEM images of vinyl records that we all have seen are taken at very low magnifications for a SEM. More serious vibration isolation is only an issue at very high EM (particularly TEM) mags. I don't know much about audio, but I have been in charge of SEM facilities.

One could also argue that because there is Brownian motion, therefore, record systems should be cooled to as close to absolute zero as possible. I was actually thinking that OMA could reduced sensor error by using a Peltier cooler on their electronics. Zeiss light microscope cameras do that. I have yet to see active sub-ambient cooling in audio.

And last but not least, even if it is measurable, is it audible? I don't think I have seen blind tests on equipment racks (another overhyped topic, IMHO). Or one could argue that a TT should not be in same room as the speakers. Again, I have yet to see that implemented on a broad scale.

Bottom line: it important to keep an overall perspective on things, and put them into relation to one another.

@OP and Lewm - thanks for your responses. My point in relation to SEM's was a more general one in the sense that there is a tendency (not on your part, I hasten to add) that mass negates vibration.

On the specifics, the average concrete floor is not particularly massive or particularly rigid. But I also made the point that components - but turntables particularly - are susceptible to airborne vibrations.

In the specific case I quoted Mr Fremer, by his own admission, could not hear the difference between a major part of the isolating component of the Wilson Benesch design being operational or not.  

Personally, I find that surprising IMHO etc. etc.