Help needed intermitent Audio fault in X5 2001

[ikosc]

Hi i have an X5 2001 model, lately i have been having a big problem with the sound. It keeps going off if i go over a bump and it doesn't come, unless u leave it off for sometime. I wanted to know if it have a faulty amp or the main screen in the dash is faulty and any idea where the amp is because i found at the rear below the CD changer only a box for the phone connection?

Please help it is driving me mad because it keeps going off, even when in radio mode or tv no sound to the output.

thanks