Build a Faraday cage around your equipment.

I'm with @carlsbad2 - This looks like a tweak in search of a problem.

Just to be clear, I'm not criticizing you for playing with it.  But I learned long ago not to post at this point in my fiddling....

OP certainly sounds angry...

Problems in audio are often rather evident as audible fact...

And most of the times there exist specific technical solutions for any "problem"...

But the main task is not only to solve evident basic problems in the mechanical, acoustic and electrical dimensions...

It is also to think about "optimization" of an audio system which seems to present no particular problem... Sometimes we search for a way to improve it for the sake of doing so ...

And some problems are easy to detect as problem...

But some are undetectable at first ...Because the owner had no audible idea experience about this factor which did not appear as an audible problem...

I read this post thread from the OP as a reflection around RMI and EMI and cheap ways to experiment about it... ..

Then it is more a possible optimization proposed set of experiments than a "tweaK" in search of a problem for me...

Most people for example will call a useless "tweak" any use of unorthodox ( schumann generators) or even a classical device ( Helmholtz resonators)  to "optimize" a room... Because they perceived that their room is OK already... But most of the times their room is not "optimal" at all but they dont know it because we must do the optimization experiment to know it in the first place...

In the same way, vibrations affect the gear, it is a problem but there is always ways to go further than simple classical  ready made sold solutions ... I used a combination of devices to optimize which i never perceived as a problem to solve because it was unaudible as problem when i think that perhaps vibrations is a problem...

In the electrical dimensions it is the same.... I used many unorthodox devices to optimize with succeess my amplifier but i never did it because i perceived a big problem... It was a way to optimize it... Many of this devices homemade has been ridiculed here even if they cost me nothing and they worked for my ears...

Then i welcome any good faith proposition open for discussion without rejecting people or judging them...

Is it not more interesting ?

@jea48 

Valid Points!
but as stated I am personally looking at exactly what you mention, placing a sheet of the cloth on the shelf under the device so that items directly below, above or even to the side don't spread their interference to neighboring devices.

I see VERY FEW devices that have solid boxes around them. If they were they couldn't breathe! Thus my comment that a perforated box is far superior to the theoretical solid box which doesn't exist to begin with.  And how about the exposed tubes mentioned above? Tubes are VERY susceptible to RFI.

Again this isn't meant a cure all or even that great of a problem but looking a the tens of thousands of dollars spent on specialized cabling (just one example) which only fixes minor issues in most cases, We only accept that together with all of our other efforts, we end up with the best possible sound for the least possible expense.