Reply to Humming noise when external monitors is plugged

i've plugged an external monitor to my MBP and since i did it, there's a loud humming noise. if i disconnect the monitor, the noise stops.

I tried wiring the monitor base (metal chasis) to S4 ground loop, but it's not helping. It also doesn't metter in which PDU I will plug the monitor. I'm basically out of ideas.

It's obviously a bad/incompatible power supply in the monitor, but maybe there's a way to cheat it?

Any ideas?