As I understand it, the JJAZ can certainly be used under any component - at the moment, I have some of my set under my preamp.
The $16 gets you four feet, each foot consisting of several circles, so you may actually be able to isolate several components using a single set, since you may use the smallest under one, and then a combo of the remaining circles, under a heavier component.
I quite like them under my Hagerman Clarinet.