Upper Level Vintage DD Strenghts and Weaknesses

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.

Townsend is talking about vibration coming from the earth up into the speakers. He expects the speaker enclosure to be 'solid enough' that it doesn't move, but let's not shake it (the enclosure).

That's what I need to prevent happening up to my TT from my springy floors, vibration any fool can feel.

So I use Isoblocks below the plinth that let the shake calm down by the time I walk away and the 1st track's content begins. Once the plinth is stable, it doesn't hurt to put it on something soft, thus I recommend it.

If you look at my system, photo of speaker face down with back removed, my speakers are on 3 hard caster wheels, and are angled up (see the block of wood above the 2 front wheels), thus the tops are slanted. This projects the tweeters directly at seated ear level, and prevents reflections parallel to the floor or ceiling. Toe-in prevents parallel side wall reflections. And slanted front effects time alignment if you think it matters.

Now look at the 1st photo, all the pretty things sitting on the slanted speaker tops. Vibrate/slide? Nope.

The 15" woofer weighs 37lbs, a monster magnet, the two horns are heavy.

Zero vibration, nothing moves just the cones, the air, far better than you would expect without computer designed internal bracing of any kind.

I ordered softer wheels based on Townsend's 'theory' (probably measurable, thus no longer theory). The wheel's axels were 'loose', no good, put my original ones back on.

I think you can make a mess of things trying to fix some infinitesimal ....