In my 2010 Countryman S the radio starts buzzing when I turn the lights on, even mp3 has a buzz.
When I step on the breaks the buzz is less, when I release the break the buzz is full on again.
When you turn off the lights the buzz is gone.
What happens when you step on the brakes ?
Find a good auto stereo shop and if they can’t fix it then a replacement radio is in your future.
Just a wild thought but both times the alternator in my Corolla was failing there was radio interference. Yours could be producing RF interference due to the added electrical load of the headlights.
My guess is there’s something acting like an antenna that picking up rfi and that’s what’s making the audio noise from the radio. If you have anything connected to the audio system, try disconnecting all that stuff first. Especially any cables connected to the audio system that aren’t connected to a device on the other end tend to cause this sort of problem, like a usb charger cable.
My guess is that @Som23 has aftermarket HID or LED bulbs.
If it’s the case, buzz is from the low-quality aftermarket “retrofits”.
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