I just got a 2008 Sonata Limited 3.3L with the Infiniti powered sound system with the subwoofer. I would like to swap the head unit out with my Kenwood KDC-X896 w/ bluetooth. I know that this car has a factory amp powering the speakers. What is my best option?

Converting the signal down to line level with the 4 channel converter
or
Removing the amp all together.

Also can I make use of the subwoofer some how? And does anyone know where the amp is?

Thanks.