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


Looking atFaraday cages in Wikipedia
Here's a quote:

A Faraday cage operates because an external electrical field causes the electric charges within the cage's conducting material to be distributed such that they cancel the field's effect in the cage's interior. This phenomenon is used to protect sensitive electronic equipment from external radio frequency interference (RFI). Faraday cages are also used to enclose devices that produce RFI, such as radio transmitters, to prevent their radio waves from interfering with other nearby equipment. They are also used to protect people and equipment against actual electric currents such as lightning strikes and electrostatic discharges, since the enclosing cage conducts current around the outside of the enclosed space and none passes through the interior.

Why are we trying to quiet the rfi to and from our amps, transports, etc when the metal case already does it? 

kavakat1
nonoise
A quick look at Wiki states that any hole or vent has to be significantly smaller than the RFI/EMI wavelength in order to stop it. Good luck with that. It enters through any connector not used as well as any cable not completely shielded. Also, AC brings it through your PC.

All bets are off how small or big a space has to be to stop or prevent or disallow an electromagnetic wave once the Schumann frequency raised its ugly head. You know, the 7.8 Hz wave that sets up in a listening room when generated by a Schumann frequency generator, since the wavelength of that particular frequency is around, what 26,000 miles? Yet it has no problem fitting into the room. Yeah, baby!
Geoffkait,
Since you mentioned it, I use Clone Audio's Schumann Generator to defeat all that nasty electronic smog. Better detail, instrumental/perfomer separation, layering and soundstage.

I can't wrap my head around how a 26,000 mile generated wavelength can fit in my room, so maybe only a fraction of it's length is generated since a wall wart is used as a power source. However it works, I'm glad I have one.

All the best,
Nonoise
Electromagnetic waves are very flexible. 😀 The Schumann frequency waves wrap around the room. It would have to be the full wavelength as shorter wavelengths wouldn’t be 7.8 Hz. Can electromagnetic waves enter the component via unused input/output RCA jacks on electronics, even though the chassis case is metal? I wouldn’t bet against it. It's also interesting how a Schumann CD can generate a 7.8 Hz acoustic wave in the room through any speakers, even computer speakers, no?
 
kavakat1 OP
So, would a sheet of mu-metal placed on the bottom of each shelf between components help? I have a NAD integrated amp, and one shelf below is my OPPO 105. Shelf is MDF

Since the primary culprit of magnetic fields by far is the large transformer, the ideal solution is to completely wrap the transformer with one or two layers of mu metal, which is quite flexible (and SHARP). As I recall one layer absorbs 77% of the magnetic field whereas a second layer increases the performance to 95%. A space of 1/4" should be maintained between the two layers. The correct type of mu metal is low frequency high permeability mu metal.
Mu-metal tends to lose its properties after it is bent, unless it is annealed. Same with many other magnetic exotics.