Hi
All starting to sound very confusing
I agree that when you send an input signal to the AUX or TP2 sockets on the BC9300, the DIN plug uses pins 3 and 5 for the channels and 2 as the ground
Open the DIN plug and view the connections from the solder side. With the centre pin 2 at the 12oclock position, the pin numbering is 1,4,2,5,3. Make sure that white and red go to 5 and 3 and the copper goes to 2. If this is the case then the DIN connection should be OK
On DIN connections, Left is 3 and Right is 5. Check which colour is Left and Right.
On the Mini jack, I have seen the connections numbered as follows:
Cable, Plastic holder, 3, 2, 1
Ground is nearest the plastic holder ie 3
Right goes to 2
Left goes to 1, ie the outer tip of the mini jack
That is how I would expect to see this cable connected. In your case, the copper wire to the mini jack should be at connection 3. If you have a multimeter, you can check all of this very quickly.
Regards
Geoff