Update 1: I also had a very old 230 FM radio (left and right speakers in the middle of 2 cartridges) for testing purposes connected to the adapter and realized here that through the speakers of very old radio noise is come along which to a socket in the house can not be determined are. So the power of the adapter is likely not the same "quality" as electricity from the socket have (subjective, untested opinion). Possibly Filter current device as something already standard out.
