Have you considered vibrations transmitted directly via the air? In other words, do you want a rack or a cabinet? You should consider a cabinet if you listen loud, are thinking about using exposed tubes, or especially about trying vinyl. Cabinet doors/view panels should be well made and close tightly to avoid rattles.
If not and you listen loud isolation properties that are built into the rack may be of value to you if your floor is up to it.
Mapleshade is another source for heavyduty racks with isolation benefits.
I hesitated a bit to bring this up, because it can be its own can of worms between believers and naysayers of various isolation products.
First audible factor to consider when purchasing a rack/cabinet is mass. Mass is your friend when thinking about vibration control because as mass increases, so normally does rigidity. And both factors lead to lower resonsant frequencies and therefore greater energy levels needed to excite the object to vibrate. BTW, did you know that the earth vibrates at 1 - 2 Hz?
Second factor is the floor and those vibrations transmitted through the floor. If heavy plank/timber or concrete slab supported by dry/compacted clay versus modern wood framing over living/crawl space makes a huge difference. The former is great, and you should spike into it as a firm/stiff foundation. This will couple a heavy rack to the greater structural mass, again lowering the resonant frequency. Spiking also helps anchor the rack horizontally and "short circuit" any carpet/padding.
If your floors are "softer", you've ever heard heavy footsteps through the speakers, or espcially if you are considering vinyl, you need to consider isolation from the floor. The best options are wall mounting (if no slamming doors, etc. on the wall) or air suspension. Avoid metal stud walls like the plague.
If space is available, a low/wide rack/cabinet is preferred as it would sway less (be more rigid) and be more out of the way of the imaging/soundscape. This is what the guys are after that you may have seen with all their components on separate isolation bases across the floor. I'm too old and clumsy for that. (I'd probably trip over a cable and wipe out half my system in the first week.)
