I have determined I have strong DC leakage into my AC system, apparently it saturates all circuits in the home and I"m continuing to figure out where it’s coming from. It was causing mechanical hum, surging noises in my pre-amps (not via the electronic path to my speakers). I confirmed it by using two different pre-amps. I bought a used PS audio DC Hum Buster and it pretty much eliminated the noise so that’s great, there’s a tiny bit left I can occasionally hear in my very quiet listening room. I have a second Hum Blocker; can I plug one hum blocker into another ? I’m guessing there’s no reason not to and I’m guessing the second one will remove any remaining traces of the noise?
You can and they will help but you really should contact your utility company for a fix.