Unfortunately there is a window behind my setup - can’t do shelves. So, it’s stack them or nothing. The only thing that I can do is isolate all of them from each other. At least I’m going to try.
My perception of this issue (which could be entirely incorrect!!) is that there are two issues to consider:
1) Physical decoupling of each component from any source of (microphonic?) vibration from speakers, other black boxes, etc. A good rack should help, but if you can't accommodate one, Fraim style glass on ball bearings/cups might still help.
2) Distance between sensitive source components and powerful electrical currents, such as AC supply cables and large transformers. The latter become bigger, and potentially more problematic, as on progresses up the Naim ladder, so a preamp might suffer more from being close to a 555 than an XPS, and more from being close to a NAP300 than a NAP200, for example.