The amp in the door will require a permanent power supply, that can be picked up from the permanent supply to your head unit (not the ign supply). the colour of the wire suppling the permanent power to the amp is purple but maybe light green/orange.
Also the amp requires a switched supply which will be you blue wire from the Kenwood this wire will connect to an green/orange but maybe purple/yellow wire as there was a colour code change at some time.
AFAIK - the sub/amp power supply is built in to the rest of the cars electrical system and has nowt to do with the HU. All I did was make up the RCA Patch lead and connect that to the two cores on the separate multiplug