The noise go up and down with the volume control, and when the volume control is set to 0, there aren't noise.
Indeed I have checked other threads.
I'm not sure if it's a buzzy sound. Is like a pink noise.
I don't think that I have a problem with RF at RCA because there are <50cm long and have a great insulation.
My apartment doesn't have ground and, generally, I have an old and bad electrical installation. Maybe is it?