I agree with MC, that properly loaded and damped springs are likely to be the sonically best solution given your description of the structure you reside in.
My situation is a bit different from most here in that I use individual springs under my speakers and subs, instead of the Townshend or Nobsound products. However, I went through quite a learning curve and much trial and error before finding the appropriately sized springs. I figured out how to damp the springs, and it helps that all my speakers are supported on very stiff, solid, and heavy Sound Anchor stands. In addition to removing the guesswork, the Townshend pods and podiums may be better damped and have the ability to be preloaded.
My situation is a bit different from most here in that I use individual springs under my speakers and subs, instead of the Townshend or Nobsound products. However, I went through quite a learning curve and much trial and error before finding the appropriately sized springs. I figured out how to damp the springs, and it helps that all my speakers are supported on very stiff, solid, and heavy Sound Anchor stands. In addition to removing the guesswork, the Townshend pods and podiums may be better damped and have the ability to be preloaded.