A suggestion; Why are you seemingly trying the most marginal, minimal tweak in an effort to gauge effectiveness?
Consider that by limiting the extent of the utilization you are preparing for a failed test. If you are going to test, why not test with anti-vibration under all components? If you are worried over the cost, then choose a complete set which is no more expensive than a smaller number of more "refined" ones. Even better, why not try some home-made devices (i.e. foam or rubber) to see if you can detect any difference, and work from there?
Your experiment seems congruous to someone saying, "I want to determine if cables make a difference," then setting up the conditions such that only one wire is changed.
Well, under such conditions you may or may not have success. But it diminishes the efficacy of the test, because the influence of the device may be subtle enough that unless used througout the system it may be undetected by your ears. Consequently, you may determine that all such devices are a waste of time, or that all cable changes are a waste of time, etc.
So, if you are going to conduct a test, why not go all out to see if the concept applied on a grand scale works? Usually this can be done without overextending one's time/budget.
OTOH, it may just not matter at all! ;) I have used various anti-vibration devices and "points" etc. under digital components in the past and judged them typically to be a waste of time relative to the gains to be had with changing elements of the system proper.
My suggestion when it comes to digital is to spend your efforts on influencing the signal path, not the external conditions of components.
Happy New Year, Everyone! :)
