Isolation really enhances the sound!
I am not sure what is the right or wrong method on placement as I have seen everything under the sun when it comes to this, in the case of Stillpoints; top-hat up, top-hat bottom, adapter screws screwed in under OEM foot and now throw in what I am about to say.
My thoughts are to place these wonders in a tripod fashion under the immediate area of the power supplies transformers and capacitors.
By channeling the sound out from where it is emitting potential interference would have the greatest affect. Like water or electricity, the faster it is directed, the more control you have. Bases under the Stillpoints add more dispersement as energy has a wider displacement.
My heavy amps, regenerators and other pieces weighs down itself equally on the tripods with no problem. When I used 4, it was a fight to get the 4th to seat, and later found it was not supporting the amp, thereby providing no isolation.
I pulled some pictures of D’Agostino amp line off the web to give a visual and YELLOW STARRED where I placed the Stillpoints on my Momentums, and GREEN CIRCLES represents where the OEM feet are.
Note: I think isolation is better then no isolation, and other brands will add an affect as long as there is metal to metal contact.
At the end of the day it comes down to preference - it's enough to drive any sane minded person crazy, but not the audiophile
Pipe in your theory or comments against little ‘ole me - happy listening!