Isolation vs. Absorbtion

I am new to the audiophile hobby, and I am confused by what appears to be subjectivity and contradictions. When "mounting" a cd player and other components, is it best to use Soft Pads which ISOLATE vibration and RETAIN internal component vibration, OR is it best to use Hard Cones, which DRAIN (harmful) component vibrations into shelf material. Secondly, is it best to attach shelving to racks so that shelving makes Direct (hard) Contact - OR, should the shelving be Isolated from rack? Is there a scientific, indisputable answer?