Upper Level Vintage DD Strenghts and Weaknesses

@billwojo the plinth that came with the drive, two arm boards. From Elliot's virtual system photo, it appears to be the same. I put a new teak veneer on mine. Waiting on drive from JP. Should be soon. 

As said previously, the Types of Footer under discussion are not only referred to for the improvements thay are making when used with a TT Support or as a Cabinet Speaker Support.

A friend is using IsoAcoutic Pods under their Electostatic Loudspeakers.
They are veru greatful to my introducing them to, and loaning the AT-616 and the Feet of Silence.
As this triggerd their research into the available options to mimic the impressions that were left from the loan period.  

I've said this before, but I do not see the benefit of using spongy or springy feet under any loudspeaker.  I see only negative consequences, because some of the amplifier power delivered to drive the speaker diaphragm will then be used up in rocking the speaker back and forth.  That would result in a loss of speaker efficiency but also in an increase in distortion and possibly a high frequency roll-off.  For that reason, I believe speakers should be firmly anchored.

What is a "Townshend Podium"? Is it based on an inner tube (i.e., compressed air in a bladder)? If so, that might not be as deleterious as some other footers actual using springs or rubbery compounds. My objection is based on theory; I have never tried it and don’t intend to as the speakers in both of my systems are physically huge. (Please don’t jump on me for advising against something I have not myself tried. It is just anyone’s natural tendency not to do something that seems like a bad idea.) Also, if bass frequencies are relegated to an outboard woofer or subwoofer (as for one of my two systems), then the negative effects of a springy suspension on the main speaker would be ameliorated, I would think. Finally, any negative effects that I describe might in some cases be below the level of detection, unless one compares a very rigid support with the springy type of support. Problem is that many speakers are not well supported by their solid feet to begin with, so replacing inadequate solid footers with wobbly feet is not that detectable at the listening seat.  But I just cannot get my mind around the idea that speaker designers spend so much effort rigidly mounting drivers in very thick and robust cabinets, stiffening them and touting non-resonant materials, etc.  How then can it be a good idea to stand the speakers on a deliberately unstable base (in the lateral plane)?  How could you not be dissipating amplifier energy in moving the speaker back and forth?  On the other hand, if one likes the net effect, that is all that counts. I certainly am not upset either way.