Be aware that using multiple layers of isolation materials can have a negative effect on vibration isolation. For example, if you have two platforms and two layers of isolation material, this is equivalent to a two-mass/two-spring system of coupled oscillators. This system has two resonant frequencies instead of one (so-called normal modes or eigenmodes). One of these normal modes will have a natural frequency higher than that of the equivalent one-mass/one-spring system and the other will be of lower frequency. Because the natural frequencies follow a sort of fractional power-law dependence on the masses and spring constants, the eigenfrequencies are not far (within an order of magnitude) of the value for the one-mass/one-spring combination. All other things being equal, this is not what you want because the goal of effective vibration control is to keep the natural frequency of the isolator well below that of the system that you are trying to isolate.
I have gotten excellent performance from Minus-k products both in my laboratory and in my home audio system.
I have gotten excellent performance from Minus-k products both in my laboratory and in my home audio system.