2001 Dodge Caravan Head Replacement

I would like to replace the Head unit in a 2001 Dodge Grand Caravan.  This has an infinity gold system.  Each speaker appears to have an amp on it except two small speakers in the back.  There are a total of eight speakers in the van.  Does anyone know what powers the amps - voltage, amps, ohm rating, etc. -.  I have tried buying a "wiring harness" that is supposed to allow hookup of any head unit.  This wiring harness included a black box for input and output to the old wiring harness.  I still get no sound, period, out of the speakers.  My concern is that the head unit does not put out enough voltage to power the amps.  Each speaker has six (6) pins on the amps.  2 wires come out of the black box amps into the speaker.  The other 4 are a mystery.  According to the wiring, one is positive and one is negative, and they are in line through the speaker to the next speaker in the set.  This eventually loops back to the head unit and the ground, according to the diagram.  I just want to replace the head unit without having to rewire the whole damn van.

Thanks

With my past experience with these vans, you are not trying to power the amplifier's with the internal amp of the aftermarket deck. What you are doing is send a signal to the speaker and what's probably happening is your not turning on the OEM amplifier with the aftermarlet deck. You need to power the amplifier's first before you get any power from them.