The only incidence of wired interference I have personally experienced was a ground loop in a car (car cigarette lighter-usb adaptor-usb cable-phone-aux cable-a

The only incidence of wired interference I have personally experienced was a ground loop in a car (car cigarette lighter-usb adaptor-usb cable-phone-aux cable-aux input on car stereo). I seem to recall fixing it with a <$5 component that isolated the signal, this was about 10 years ago and other vehicles I've owned haven't had the same issue.