Now I have video/mouse EFI noise in my system!

[Wungun]

So... Separated the grounds of the PC and the preamp. Preamp is on the amps powerbar, and everything else on another powerbar from a different outlet.
It's a bit better... The video disruption noise is much lower, but it seems like there's a 60Hz buzz now....

 

[phofman]

Are you sure the outlets ground pins are not connected to a common grounding wire? Or perhaps to the neutral line (only 2 wires network)? I find it hard to believe the ground pins in the outlets would be left unconnected.

 

[Wungun]

Are you sure the outlets ground pins are not connected to a common grounding wire? Or perhaps to the neutral line (only 2 wires network)? I find it hard to believe the ground pins in the outlets would be left unconnected.

This outlet box has the bond wire to earth cut...unbelievable, I know! Lol
The neutral would be connected... All of them in the building would be connected eventually at the junction box.