Bigtwin:
"Stunning that some of the isolation units for speakers cost more than some speakers I've owned. I'm sure the law of diminishing returns applies to these"
Simply not correct. Critical Mass Systems footers are so much ahead of all other isolation devices (I've tried everything) you should think of them as component upgrades.....in that context they are great value.
One more point: any kind of rubber is bad (including the long fibre jobs like sorbothane) anywhere in your support system. Forget all that BS about rubber converting vibration to heat. Rubber does not absorb, but simply returns a large portion of the bad vibes after a slight delay. This is far more apparent as you move up the sound quality gradient.
Best wishes
Aubrey