If sufficient isolation is achieved for every component, the importance of the rack itself is minimized. Maybe not completely eliminated, but close enough for Rock ’n’ Roll---a classic musician’s joke. Audiophiles tend to drive themselves crazy, trying to achieve that last few percentage points of sonic improvement. And all in an effort to reproduce what is highly compromised sound to begin with. Does that sound anti-audiophile? High performance systems are often far better than the source material played on them. A system is only as good as it’s weakest link, and once a system has achieved a "certain" sound quality level, that is generally speaking the recording and/or storage medium. What level has to be reached for a system to be "good enough" is of course a very personal one.
MG’s basic premise raises the interesting question of how much of any given component's sound quality potential has been realized in the basic design and build of the piece, how much that potential can be more fully realized, and by what means. If can be argued that the less a component’s sound can be improved with tweaks, the better it has been designed and built. Is any tweak going to make up for a, say, power amp’s poor power supply? Would the money spent on expensive tweaks be better spent instead on a better amp? I’m just askin’.