Sota Sapphire and Isolation?

@lewm  Ok, fair enough.  But the shelf itself still vibrates, which is why people use isolation devices on a shelf, under a cabinet, etc.  The question then becomes which is worse, the vibrations from the shelf or the potential resonance from the spring footers.  That’s not knowable until you try, and since there’s zero risk again I ask, why not?

The Merrill Heirloom TT has a spring suspension and I use the GEM Dandy 

60 Durometer Decoupling Foot under my table , at the same time I use a wall mount TT platform to totally eliminate footfall vibrations from a wood floor .

One can jump up and down or play the music loud with the deepest bass notes without issue .

Do whatever you want. But do realize that the built in spring suspension of the SOTA is there to filter out all the stuff you’re talking about where it counts, before it can disturb the platter/bearing/tonearm/cartridge. I’m not saying it’s perfect, but adding a second independent spring suspension to the closed system can only interfere with its function. This is demonstrable with math and physics, not just a matter of my opinion.

Spring on Spring is not without risk of very high gain low frequency feedback as constructive and destructive resonance will happen… Look for ( failed ) example of double sprung car suspension…. but hey…. 

I’m not saying it’s perfect, but adding a second independent spring suspension to the closed system can only interfere with its function.

@lewm Due respect, but you can’t know that as there are too many variables such as it’s not spring on spring — it’s spring, footer, plinth, then the sprung suspension.  There’s no mathematical or physical model for that combination, and there’s no way of knowing how the resonance frequency of the footer springs would interact with that of the suspension, so again just too many unknowns.  And as you say, the SOTA suspension isn’t perfect so the big/ultimate question is really if significantly minimizing shelf vibrations could have significant benefits that may (or may not) outweigh any negative spring resonance effects and absolutely no way of knowing that without trying.  If it’s me I’d try the spring footers just because no risk/cost to do so then I’d try a thick butcher block that’s cheap as well, and then I’d try something like a Ginkgo Cloud or other absorptive platform and see which combo sounds best.  Always fun to experiment and learn, and often the results can be surprising and counterintuitive.  It’s kinda like implementing room treatments and figuring out the right combination of absorption and diffusion — you can digest all the theory you want, but you’ll never know unless you just try different combinations for your specific situation.  Anyway, at the very least there’s some good food for thought for the OP to chew on here.