Hi, San Marcos. Magnetic levitation of audio components seems like a good idea, but has major drawbacks. It effectively blocks vibrations from passing from one surface (the shelf) to another (the component) and vice-versa. However, these devices have little or no capacity to attenuate vibrations of the component itself, which is of primary importance to component isolation. You need both, to block vibrations and to absorb vibrations. Magnetic levitation is very slow counter-responding to vibrations and is virtually useless in this regard.
Micro-vibrations are generated internally within all electronic components, by alternating electron flow and heat, and other electronic functioning. CD players, of course, also have motor vibrations and CD spin to deal with. As vibrations are perpetually generated, they cannot be eliminated, but their adverse effects can be minimized by damping the chassis.
The photos on the linked page expose a major giveaway to these devices' shortcomings. The magnetic footers are placed UNDER the components' factory feet! Thus, you're still relying on the rubber feet to a degree, with rubber's inherent resonance and reverberant issues. In fact, by unconstraining the factory feet, they are unleashed to resonate even more freely and introduce all kinds of sonic anomalies. Magnetic devices can't be used in direct contact with the chassis of many components (like those pictured on the linked page), anyway. Any electronic element or signal path (wires) in close proximity to a magnet will be adversely affected. Music will sound okay at first, but as time passes, the magnet's field will soon affect the magnetic flux of the signal path adversely and render the music terrible to listen to. I've surely experienced this firsthand.
Tenderfeet in intimate contact with the component chassis will do a better job. Tenderfeet have a very rapid response to absorb micro-vibrations and block the transfer of vibrations, enabling a truer electronic signal flow.
Magnetic devices will find circumstances where they perform brilliantly, applications where they are a total bust, and varying degrees in-between.
Steve
Herbie's Audio Lab