I tried searching for a solution first but none seem to have the same problem as me.
Car: '95 gsr
HU: kenwood ddx 6019, with navigation.
Problem: Just today this started to happen. I was on my way to class and listening to a cd. When the sound gets softer and softer then nothing comes out of the speakers any more. If you shut it off for a while and turn it back on then you get music again. This time it only lasts a few minutes then music gets softer and softer and then the sound goes out. I have checked all the wires, all look good. The HU stays on, it works but no sound.

 

Sounds like you may have a short in the speaker leads or a speaker, or possibly a poor power or ground connection. 94