The best situation is when vibration has an easier time travelling in one direction and a harder time in the other. This should be the case when you use spikes under your equipment. The reason, I believe, is that you are creating a situation where there is low physical impedance from your equipment to the table, as the small surface area of the tip creates high effective mass (by making your equipment seem much heavier to the table). There is then high physical impedance for vibrations going from the table to the equipment, as these vibrations now have to travel up into what seems like a heavier object.
To couple or decouple? That is the question.
This is one of my favorite subjects and pet peeves.Is this just a matter of semantics or a misrepresentation of the principles applied in the set-up of equipment. My experience tells me that coupling is what you work for. This is the principle that is expoused in the early Linn literature. The mechanical connection that doesn't introduce or take away any information. This seems important with componets with transducers primarily turntables and speakers. Different materials, like sorbothane, are used to attenuate frequencies but are used in conjunction with metal cups to physically couple to your stand, shelf, floor, etc. Coupling also allows mechanical/acoustical energy to travel away from a componet. The designers at Mission in the early 80's were right on to this. Questions or comments please.