Tjassoc, I would add one more factor in your sources of contamination of our ac lines, namely power companies using the power lines for communications. I have seen the modulations on an oscilloscope.
I would add one new factor to what might be used to cleanup the contamination, not ferrite beads, but rather Hitachi FineMet beads. Thanks to a friend with ties to Japan, I have heard the impact of these on the resolution I get in my audio from putting a short power cord pigtail with beads on the three conductors. It is totally awesome. Occasionally, you can find these beads at surplus shops on Ebay. That is where mine came from. Hopefully, there will soon be a source to get pigtails or powercord with such beads.
I would add one new factor to what might be used to cleanup the contamination, not ferrite beads, but rather Hitachi FineMet beads. Thanks to a friend with ties to Japan, I have heard the impact of these on the resolution I get in my audio from putting a short power cord pigtail with beads on the three conductors. It is totally awesome. Occasionally, you can find these beads at surplus shops on Ebay. That is where mine came from. Hopefully, there will soon be a source to get pigtails or powercord with such beads.