Good to know Elizabeth as I was considering buying a set to trial.
I received an order from Herbies a few days ago and my results are puzzling.
Bought 3 isocups and lamp black balls to place under my Ayre ax7e amp.
So placed under the chassis bypassing the existing 3 feet wrought a slight increase in depth and bass.
However placing under the existing feet gave a considerable change! Much improved bass and top end, almost like I had hit the loudness button...lol.
I thought the idea was to bypass the manufacturer supplied feet and go direct to chassis.
Tbh I was truly surprised to be really hear anything this noticeable. And I swapped back and forth many times just to be sure at least in my mind.