High End Isolation - HRS, SRA, Active platforms

I personally use Symposium Ultra shelves and solid couplers under my amplifiers and linestage, and Svelte Shelves under my speakers. I am particularly happy with what the shelves do under my speakers (tighten up the bass and improve clarity).

But, these and any other isolation devices are "tuning" devices and can alter the sound in both positive and negative ways. In particular, I've heard such shelves used under CD players that made the sound dramatically drier and analytical sounding. It would be simpler if "more" or "better" isolation was always better, but that is just not the case. One has to experiment.

A friend has a massive, three section HRS stand and separate amplifier stands from HRS. I cannot really say how each affected the sound, but, his system sounds very good with these items. The big component stand is incredibly well built and beautiful to look at; what else matters?

I disagree that a rack is designed only to isolate components from vibration coming from the floor. Most rack/shelves are also designed to dissipate vibration coming from the component itself (e.g., the vibration of power transformers). Couplers are used to transfer the vibration to the shelf and the shelves are designed to convert the vibrational energy into heat. Tap the case of a component coupled properly to a well designed shelf and one just sitting on rubber feet on an ordinary rack and you can hear a big difference in how quickly the vibrations are deadened with a good shelf/rack.