Seems like any equipment in a metal case is protected from rfi

That's very good. The Morphic Message Labels are in the mail.

RFI/EMI is a tricky beast to handle.

It is nearly impossible to make an enclosure 'tight'. As a former designer of military electronics that were required to survive EMP, it's quite a challenge even at much smaller audio scales. 

Thing about EMI/RFI susceptibility re: audio is all electronics - tube or SS - can convert very high frequency noise right down into the audio band via diode demodulation. And the higher the frequency, (like the microwave from cell phone systems) the harder it is to deal with.

Top issue for EMI entry is cabling to/fro the chassis - these are the real problem children. RFI walks along the cable skin and enters easily to your gear's nice metal box via audio connectors never designed for susceptibility control. Once inside, the RFI radiates all over using internal wiring. Even shielded cables, - although better than open wire - are nearly transparent to RFI at very high frequencies.

Re-engineering existing equipment is virtually impossible as to get real, testable results.

Another "enlitened" response. We have to start thinking outside the metal box and I really can't recommend enough the use of a Schumann Resonator to help defeat electronic smog. 

If you can get a hold of one it would be so easy to try and see if you can detect the benefits. Just place it close to and higher than your head when you sit to listen (5'or more is best) and set it up so you can easily unplug it at will. Listen to some very familiar recordings and judge for yourself. 

All the best,
Nonoise

enliten
RFI/EMI is a tricky beast to handle.

It is nearly impossible to make an enclosure ’tight’.

>>>>>Especially with all those unused Input and Output jacks. 😛 Then there is the issue of RF generated by microchips inside the chassis, as I pointed out, was it yesterday? Think inside the box!

As a former designer of military electronics that were required to survive EMP, it’s quite a challenge even at much smaller audio scales.

>>>>of course EMP is not the same thing as RFI/EMI. Be that as it may. And it’s not that difficult to deal with RFI/EMI in high end electronics. Audiophiles have been doing so for many years. A good start would be to power OFF all unnecessary appliances such as fridge, TV, room purifier, even a microwave oven in sleep mode generates RF. (It helps to have an RFI/EMI meter to, you know, see what you're up against.

  You could also consider Stillpoints ERS shielding sheets . 11x8 for $25, at Music Direct . Lay a couple on your equipment and see if you can tell a difference . Then attach in a semi permanent manner. Also when my sound is too tight , I switch from briefs to boxers 🤡.