Ya know, it's funny, but I've
never seen any Head-fier using it for their stack, but silicone sealant is absolutely
ideal for creating a semi-permanent stack that perfectly protects the individual devices from abrading against one another. It adheres beautifully to metal, glass, plastic, etc., and does not let go, in normal usage, but most definitely is willing to let go when deliberately prised apart. When it is, eventually, deliberately removed, it leaves no marks or damage, whatsoever. It also moulds 100% perfectly to whatever shape your devices are. It's also resilient to amplifier heat, and, provided you take care to get a low-acetic acid formulation, is perfectly harmless to almost any material one's devices may be made from, and the end result is, essentially, non-toxic for daily contact with your hands/fingers.
If you think about it, the glass panels of fishtanks are often 'glued' together using silicone.
Just a thought....