Again, caveat that someone with more knowledge should chime in, but here's what I think you should do:
Route the signal wire going into your factory amp to your AudioControl, which probably has RCA pre-amp outs. Run those RCS to your amps and you're good to go. If you are still powering your mids with the factory Bose amp just tap into the pre-amp wires instead of doing a complete reroute. You should be good to go. I'm just not sure what the effect of sharing preamp signal among multiple devices will be.