07 yukon xl denali w/nav and Bose, add a sub

I am looking to add an aftermarket sub in place of the factory unit mounted under the center console but i also want to add an external amplifier and bypass the factory Bose amp. I also would like to bypass the factory amp completely and upgrade the factory speakers but i want to retain the dsp for 5 channel audio. I heard that the factory Bose amp provides the dsp also as well as it handles other features like the voice guidance. Can the factory amp be bypassed or can it be modified to have preouts installed in place of the line level outputs to run external amps?
Thanks,
    Chuck