Can you clarify what the problem/solution was? I can't quite figure it out from the picture captions.

On the OEM-1 wiring harness there were two blue wires. One of them was pure blue, the other one was blue with a white stripe.

The instruction sheet on the OEM-1 harness very clearly stated that the pure-blue wire was the "Amplifier trigger" (sic). The Blue/white wire was said to be the "Power antenna".

Tod's car does not have a power antenna. In fact, the opposite-side harness on the OEM-1 had only an amp remote wire sticking out of it, not a power antenna connection wire. So I assumed that the power antenna wire on the OEM-1 was unused in Tod's particular case.

It seems as though the instruction sheet had them backwards. When we hooked it up, there was no sound coming out of the amplifier, because the blue-white wire was not connected to anything. Connecting the blue-white wire to the empeg's blue wire made everything work. It appears as though the blue-white wire was the amp remote wire, despite what the instructions said. So I re-soldered it so that both of the OEM-1's blue wires were connected to the empeg's blue wire (just to be absolutely sure), and now all is well.