How to isolate turntable from footstep shake or vibration

Tube guitar amps provide a range of tone from very clean to smooth, controlled distortion. Microphonic tubes become very obvious in a guitar amp, yet rarely occur. Read a review of any tube guitar amp and you can learn something about them.

Wolf, as you probably know better than I, if you actually play guitar, guitar amps are distortion generating machines. The distortion is intentional. This is one reason why overstressed tubes are preferred by the cognoscenti in guitar amplification, unless you disagree. One form that that distortion takes is due to the microphonics of the tubes adding to the other distortion generating characteristics of the circuit. Don’t you think? Speaking for myself, when I hear a really prominent electronic guitar solo, I think I can hear components of the distortion that are due to tube microphonics or are very characteristic of distortion caused by microphonics. I just don’t think there is much effort to avoid microphonics from guitar amplifiers in general. 
Furthermore, I and others have been saying all along that microphonics are more or less of a problem with certain tube types and with tubes used in circuit in different ways. Hi gain tubes that have a large glass envelope tend to have the most problems with microphonics. Small nine pin miniature tubes like mijostyn‘s 6922s are perhaps a bit less prone to microphonics, but Atma-sphere seems to disagree. Tubes used as cathode followers, i.e., to convert voltage into current and add no gain are less prone to microphonics. If one cannot hear a certain kind of distortion or noise in one’s audio system, that does not mean it is totally absent. It just means you can’t hear it. Which often is good enough.

A wall rack is a good idea. A rack on a load bearing wall even better. When I was just out of college I put my Sota table on a granite slab that was pried off the front of a building that was being torn down. The slab was placed in a window ledge with rope suspending/anchoring the front of the slab to the top of the window sash. PARTAY!  The cool thing about the Sota tables is that they are reverse sprung - the spring doesn’t compress, it is suspended. Good luck

Ah, another happy Sota user. Hope that sash doesn't break! Very creative though.

@atmasphere, My Sota has always been on a sturdy cabinet. The new one will be on a granite countertop sitting on a cabinet made of 1.5" walnut plywood loaded with over 1000 records on top of a concrete slab. 

Seeing that distortion on the oscilloscope certainly indicates a problem with that Sota or the way it was set up. Could be an interaction with the Sota's suspension tuning and the mass of the tonearm/cartridge with the cartridge compliance. It would not be airborne as that would not quiet down when the Sota was placed on a better rack. 

I have an oscilloscope program so when I get the table I'll have a look and see if there is any unusual distortion at various frequencies.