Sebidoxic

I know the rear signal is split and the low bands are filtered out to the subwoofer, but do the tweeters pick up power from the front speakers and filter out the lows? Going to be installing an aftermarket double DIN on top of a Nakamichi amp and trying to figure out all the details. The aftermarket harness only has two channels (F/R), so I'm assuming this is how the tweeters pick up power. If that's the case, I'm assuming the 33w x 2 channels are sharing their power?

Also, I've searched high and low for a good write-up on an aftermarket receiver utilizing the Nakmichi amp, but have only found guides for the GS and SC. Any help would be much appreciated, because the process differs significantly from the Pioneer systems.

I'm also looking for a wiring diagram for this specific amplifier as I've had no luck finding one.