integrating aftermarket amp on ct200h

I have a 2012 Lexus CT2000h with the premium audio and nav. I installed a JL Audio XD 700/5. I kept the factory amp installed (necessary for the factory head unit to function). I spliced the speaker outputs from the factory amp to the JL amp. My problem is this: the factory amp has a low pass crossover on the front door 6x9 speakers and a high pass crossover on the dash 3.5 speakers and A-pillar tweeters (these are wired in parallel by the factory). I want to combine these 4 factory front channels into the standard 2 front channels for my JL amp. The rear factory channels are full range so no issues there. Can I just splice the high and low factory channels together and run them to the JL amp? Or do I need to use a processor like JL's Cleansweep?

yea you will need something like a cleansweep to make a full signal out of the factory filtered audio signals. cleansweep is not your only option though, rockford makes one and audiocontrol i think makes one and i think JBL makes something to integrate factory systems.