That is a Re-q from mtx, there might be a manual for it on mtx.com ? Those are processors made for hooking up an aftermarket amplifier or subwoofer to a factory "premium" audio system that does screwy stuff with the sound. The Re-q attempts to get you a flat and linear output signal and also a remote power on lead.
Best bet of course is to entirely delete the mach system... It's not modification friendly unless you are a serious nerd
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