power cords with active shielding

@kijanki 

I have a police station down the street, and a fire station down one block from me.  So the public safety GSM band would probably be in high usage during the daytime (like what I experience now).  I'm up at early hours to enjoy my system (when the city is asleep) and there are no sirens to be heard.  The subway still comes and sometimes I hear the noise, we have cell phone service now down in the subway system.

I wonder if the FCC would listen to my case?

@jea48 

Not yet on wrapping the speaker cable.  I need to get more aluminum foil, then I will try that. 👍🏻🤓

Jim, speaker cables are antennas for the electrical noise since amplifier has low output impedance only for low frequency signals.  Induced noise enters amps input thru the feedback loop.  

As for the ferrite - on one hand you need highest permeability, but on the other high frequency response.  Self Resonant Frequency (SRF) specification might be useful since above this frequency impedance of the choke for common mode signals will drop like a rock.  Read this:
https://www.coilws.com/index.php?main_page=page&id=128

I've been once in the company that had so much of the noise pollution (multiple high frequency seem welders) that nothing worked - not even telephones.  Technicians there told me that common rules, like grounding shield on one end only don't even work. At the end they had to put every power cable in conduit.  We had to put our equipment, we sold them, in the metal NEMA box with metal mesh screen on the front door glass.