I have that combo and I got it working the way I wanted after some trial and error, (the only approach available to me with zero computery knowledge). Apparently there's some mistakes in the manual. The way I have it set up, it outputs to the speakers plugged into the back unless I stick headphones into the front, in which case it outputs the sound to the headphones only. The way I understand the mics, is that it would take sound from both sockets simultaneously, or wouldn't there be some sort of jumper routing front to back mic pins?
Going from memory I think I did it like this:
Pull both those jumpers off that connect front panel to back panel speaker output.
Mic bias <-> left mic
mic <-> right mic
ret L <-> right line out
ret R <-> left line out (both of the RETs went on the lower row of pins).
the other p160 left plug <-> the other karajan right
the other p160 right plug <-> the other karajan left (the upper row of pins)
ground obviously goes into ground.
When I plugged it in the intuitive way (left<->left, right<->right), it reversed the headphone stereo output, which resulted in my being shot in the back of the head since i turned the wrong way.
If I remember rightly the left plugs should go in the middle column rather than their natural column at the far side, (where you should input the right plugs).
Hope that helps despite my inability to remember the correct names for everything.