sound problem

My friend was driving around today blasting some music. Then (not to anyone's surprise) the sound went out. The car is a 1999 525i with the premium sound system. We can hear a click when the radio is turned on, but nothing else, not even static/hissing. We are guessing it was the amp. I told her to check and see if the amp has any fuses. Any other suggestions before she replaces it?

Have the exact same problem. Replaced my amp and the radio still has no sound. When I close all the windows I hear a very faint sound but it's like someone pushed the mute button. Very frustrating. Any help would be greatly appreciated.