I have tried them. Twl's concern is valid -- but there is sufficient distance b/ween the magnet & the component & the magnet is not very strong.
I found them difficult to set up; my equipment is uneavenly heavy (massive front plates, etc) and supporting & levelling was difficult so I had to use four of these.
When I finally DID get it working, the results on my cdp were commendable: more "air" and more noticeable upper extension w/out detriment to bass. If anything the bass was more defined. I can'r say if subjective prat was better...
Better results with the pre -- where the imaging improved in the sense that it became "sturdier" (am I making sense).
The BEST results were using these under the PS (cdp & pre).
I never succeeded in supporting my TT, so no comments there.
However, I obtained subjectively "better" results (to my ears, in my system) with simple Neuance shelves on cones...
BTW, I couldn't detect sideways movement with the magix, i.e. they're not rickety. But they ARE very expensive...