Where to use Isolation devices

The purchase and support of products that Claim to isolate should be a buyer beware alert. Isolation only exists in the absence of matter. Products that claim to isolate are a failure from the start based on such a premise that cannot deliver. At best these products merely re-tune your system to the flavor of the day. Mixing several of these non -isolation products together is the audible equivalent of trying to eat a soup sandwich. Resonant energy is still trapped and slow to leave it really needs to be provided a grounding pathway. Tom

Re-tuning or, better, correct tuning is perfectly fine with me. What is correct? Well, I trust my ears, the ears that actually listen.
One Kone and two corks? That's funny but why not if it sounds right? Somehow I doubt it though.

I found using Herbies Tenderfeet under Digital, and Isocups under all tube equipment has made me stop thinking about isolation, and that is worth the price of admission (whether they make a difference or not).

Another tangent that I've found unfortunately true is the placement of third party footers under any component. Initially trying the logical route of placing feet under power supplies, transport mechanisms, etc did not always end up being the optimal configuration. Also, I can hear slight differences that are usually a matter of give and take (ie in one configuration bass is more solid but sound is muddier, opposite for another configuration). Experimentation can be maddening. But I have, for the most part, consistently heard a difference with using after market footers. Many times not necessarily better.

I wouldn't call the experimentation maddening, but it certainly takes time and patience. In my limited experience I never found stock feet to be good enough, just as stock power cords. But I don't own really expensive equipment so maybe at that level results can be different.