[timpy]

Reading the thread for the first time, all of the symptoms pointed to the signal wiring somewhere before the amplifier, and the fact that you heard whistles and pops from the speakers even when the music didn't get through means the signal is being lost before it got to the amps, as someone else has said previously.

The trouble with broken wires in the signal loops to things like amplifiers is that most amplifiers tend work with fixed gain, and high impedance inputs (such as the signal input to your amplifier) work very effectively as antennas when they are allowed to "float", which is why you can hear whirring and clicking and popping through the speakers the time amplifier loses its "reference" i.e. the signal wire and / or the signal return disconnects itself.

Personally I dislike DIN connectors for reliability in places where they see vibration and / or humidity. You've found the fault in the signal lead with the DIN connector, and because of the way the pins work, once they make a poor connection they're hard to clean up effectively. Depending on the number of pins, playing with the wiring in the back of the plug isn't funny either. I'd replace the assembly if possible.

Good luck with it