What exactly are you trying to connect the 4x2 Japanese amp connector to in your cab? I just finished hooking up my 2L12B JPN control panel to a Naomi Uni with molex connectors and the only challenge really was the 4-6 buttons for 1P and 2P. Had to wire the Japanese 4-6 button CP 4x2 loom to my yellowish orange 3x3 molex connector in the cab. Pinout of the 3x3 molex connector was something like
456
xx4
56x
had to share a ground with the 1-3 1P loom as there was no ground in this connector... I'll double check my wiring tomorrow to be sure...