Question : Grounding and RF Filters!?

[moalla]

I still have some grounding problems and learned to solve it it´s like to balance the pressure in pipe systems, and a totaly symmetric grounding line will fix it firstly.
But now in my new studiospace (300year old house) electricity 50years old at some points only 2 cables with grounding included how people builded in the past, what helps the best way to filter the incoming ac power, that noise from the washing machine in another flat or the fridge is no longer a problem. There is still one power plug what´s okay the rest is shit, but how can i separate the displays, or the bass amp connected to the weak electricity best way that there will not the next small noise interconnect grounding loop via hdmi/dvi connection?

Would a small RF filter for around 10bucks work, or does it need more to sieve the incoming power?