I worked as a musical instrument technician for ten years and got my first amateur radio license when I was 12 years old. I know about Rf.

Don't insulate your pipes. They are supposed to be grounded. Any Rf picked up by them goes to ground. Also don't bother with the house wiring or circuit breakers. It is not originating from your wall ac.

It comes from inputs to your amp or the amp itself. All it takes is for one diode in your amp or keyboard to act as a detector for RF and you get to listen to the radio for free. The mic leads and input leads from your keyboard become the antenna. Don't bother with speaker output wires they go from the amp not into it.

Do you get radio with just the pa turned on but nothing plugged into it?

Do you get radio with just the mic plugged in?

Do you get radio with just the keyboard plugged in?

Do you get radio with the keyboard cables plugged into the amp but not plugged in on the keyboard side?

Does your keyboard volume level make the radio louder?

You need to isolate where the signal is coming from. Once you have figured that out then you can take corrective steps.

Sometimes just rerouting the input cables is enough. It may go away with changes in the atmosphere. Make sure all grounds are in excellent shape. Do not use a three to two prong adaptor on anything. Use quality shielded cables on all inputs. You could line your walls with grounded chicken wire but that is pretty extreme.

After I isolated the input source of the radio signal I would experiment shielding things with a roll of tin foil.

good luck

Tom