One of my two pairs of these headphones, had headphones that didn't work (you don't need the headphones for the
AC3 decoding, only the decoder module). Well I had discovered that the wire going to the headphones had been cut, and since I was also interested in trying to extract only the surround channels (to get crowd noise without commentary out of NFL game feeds), I decided to try to strip the cable, and try to find the wires for the individual channels. Found about 4 groups of extremely fine wires (each group had about a dozen fine wires spiraled together. I thought that these must be the shield for a center conductor, but when I un-curled the wires, there WAS NO center conductor, just the fine wires. Plus, these wires didn't seem to be insulated in any way, unless they had painted on insulation like magnet wire. I looked at the ends of the cut wires under magnification, and one of the fine wires did look like it MIGHT have a core of a different material, but I can't beleive a wire this fine can be the main conductor. So the only thing I can figure is that the fine wires must all be coated magnet wire, and one of the groups must be a common ground. I've never been very good at getting the coating off magnet wire, so I decided to try opening up the plastic bump in the wires that came after the plug that goes into the decoder module. Turns out that this thing was a circuit board surrounded by moulding plastic. I was able to peal off the plastic to get into the circuit board, and it revealed what looked like about 6 surface mount resistors that seemed to feed the wires, so I'm guessing my best bet would be to tap into those resistors to look for the individual channels.
Anyway, for anyone wanting to tap into the various channels of these things, I recommend going into the plastic bump on the wires, because it was pretty easy to peal the plastic off the circuit board by poking a knife in from the side.