If you're planning to use Bose amp, then get the Hi-low conventer...
why...?
this is more fundamental knowledge on car electronic..
all amplifier is design to accept signal from the headunit.
(some have built in hi-low converter, that's why certain amp can accept speaker level input)
And almost all aftermarket, has high output wattage these day.
And if you feed these(high output wattage) to your amp, if will fry your amp and who knows what other complication . . sooner or later..
Also there is no way to rewire Bose Amp to fit aftermarket headunit..
that is just bull, what are you trying to accomplished by re-wiring.
Bose Amp on my car has 7 channel
and is configured specifically for specific bose speaker.
2 front dash (with specific freq program), 2 front door midbass speaker,2 rear door midrange , 2 rear shelf midrange, and 1 rear shelf bass unit.
And if you're planning to use aftermarket speaker, then get Aftermarket amps, or connect your aftermarket headunit to the aftermarket speaker directly... (bose speaker rated at 2ohm)
Aftermarket headunit is rated at 4 ohm impedance, so does 99% of car speaker.
It is very important to understand the concept before playing around with car ICE , especially car electronic getting more and more complicated these days.
The last thing you want it to have short in your electrical system.
Regardz,