First thing you need to decide if you want to drain or isolate. Basically you need to deal with airborne, vibrations from the floor and vibrations emanating from the equipment itself. Springs might help with floor vibrations which are probably the least significant but wont help drain any energy. Rubber and similar may suffer from some of the same issues. My thought would be to drain the energy as effectively as possible. Likely you will appreciate different treatments on different components. I doubt it will be a one size fits all scenario, but wood would not be my first choice for a shelf medium. Better than nothing is not necessarily a truly good solution.