Radio module or MID problem? - creaking sound

[Kisu_san]

I have 2002 X5 3.0i Euro model. I have problem with audio system, some time ago radio used not to turn some times. Now it is giving creaking sound with the music from all speakers. This is same for Radio/CD/Cassette players.

I took it to local garage, who said it is Radio module problem and said has to order the part from BMW. Then I took to BMW dealer who charged chf 250 for inspection and said its a problem with MID radio. I was really confused.

Stupid question: what is the functionality of MID radio, just to display info?

Satnav is working fine and sound is also fine. Mechanic told me that because nav unit uses only front speaker and does not use amplifier. Is that true?

Any previous experience on similar problems would help a lot.