ZERO, this happens more when you use fx loop. There's a way to put a capacitor filter before your cable plug that kills these frequencies. But can kill some harmonics too.
Have you ever heard abour Michael Faraday ?????
He's the discoverer of electro-magnetic induction, electro-magnetic rotations, the magneto-optical effect, diamagnetism, field theory and much else besides these magnetics things.
He made a apparell that can bypass these electro magnetics effects. Its like a jail that out of the structure, so the magnetic field take a run out of the structure, on his margin like rounding. Radio stations use it to cut interferences on the building and studios, so the mics can "talk" crystal clear on the radio studio near the antennas. Otherwise, you can hear the signal like in your amp.