In case someone needs it. The configuration of use with the pins in an mvs type mv4f /2f and 6f, is different, only in the audio since it comes in stereo. If you have a harness configured for monaural output and connect it directly to stereo, the effects sound louder. This because if you join (-) speaker + (+) Speaker it happens. For that solution, and the amplifier is not necessary to test it, it is to your speakers to add the ground wire in the negative, with that, problem solved.