Well, I never read this section of the RKRM very carefully and now I am really surprised.
From what I learned in my early Amiga days (more than 15 years ago) and never was proven wrong, channels 0 and 3 go to the left, channels 1 and 2 to the right and the audio connectors on the A4000 are labelled correctly and coloured wrong (red = left and white = right).
Well, this means either the RKRM is wrong or my world view is about to be reversed :-)
Bye,
Thomas