While my RP7 pre amp was sent in for upgrade, I had in its place a Schiit Valhalla 2. The Schiit picked up LOTS of EMI noise, perhaps due to lack of shielding. When I moved my wireless mouse, you'd hear a high pitched whine and buzz, and when there were bright colors on the TV screen you'd hear a squeal, as my computer is near my rig. The effect was mitigated by plugging my computer into a different oultet, but was still there. It was really annoying, but interesting. There was EMI through the air, and some carried through power cords and the like. Now that the regular pre is back in (Rogue RP9) it seems immune to this EMI, and is completely silent.
Is EMI noise in electrical system inaudible?
Read that frequencies for EMI noise are in the inaudible range of hearing. Which raises the question is electrical noise in your system Audible. Maybe RFI is a problem. Maybe a power management system is still a good idea for a system.
So many complex issues here, my tiny mind is in capable to figure this out.