<center><img src="http://pictureposter.audiworld.com/AudiWorldPics/2000/Bose_eq.jpg"></center><p>For those of you who have replaced the original BOSE amp / equalizer / crossover with an aftermarket amplifier, you should be aware that the BOSE unit includes three 2 channel power amplifiers - Woofer (rear panel), Rear Door, and Front Door driven by an internal equalizer / crossover. I've measured the signals going to the inputs (internally) of the three amplifiers. The three curves are presented here for those of you who wish to approximate the original equalization curves.
Note - Red is Woof, Black is Front Door(s), and Blue is Rear Door(s)

They use CHEAP monolythic IC amplifiers. There are three of them mounded on one PC board - near the edge so that they can use the chassis of the amp as a heat sink (traditional). This board is connected to the eq/xo board via 2X 16 lead ribbon wires. They operate on 12 VDC (there is NO switching power supply converter to increase the supply voltage) so that power per amp is no more than is available for a typical in-dash receiver.

Do you have any idea how to connect an aftermarket head unit to the Bose amp? Do I need to get a level matching widget of some kind?