Static noise coming overhead area in W212

[vynx]

Hi everyone,

I've recently been hearing some crackling noise in the front passenger area of my ride. I initially thought it was coming from some of the dashboard panels (my car 6+ years old now) and having switched over from a Japanese make where panel squeaks are common, I tried to ignore it completely. In the last couple of days, however, I managed to narrow down the source of the sound to the overhead speakers or area where the map and interior cabin light switches are at. It only became apparent there and then that the noise was audio static as opposed to panel squeaks. The noise is persistent even when I turn Audio 20 off; the only time it doesn't come through is when the engine isn't running. I'm concerned that this might be a symptom of a bigger electrical problem altogether and short of having to send the car in for diagnostics at C&C, I figured that I check if anyone else has experienced this, if there are any concerns around it and most importantly, if there is a quick fix to it.

I apologise if this has previously been covered somewhere here in the forum (I tried searching a little, but couldn't find anything as of yet). Please be patient with me as I am a first time Merc and continental car owner, so a lot of these additional features and technology in a car is quite foreign to me 

For more information, I'm driving a end-2010 E200 CGI W212. I love the ride very much and I'm delighted with the purchase, but it would be a lot more pleasant if I could eliminate this sound.

Thank you in advance for your advice!