What harness do i need to connect a Kenwood KDC-BT61U to an Audi TT MK1 with Bose system?

I have an Audi TT MK1 2003 with Bose and have purchased a Kenwood KDC-BT61U but I am unsure what harness adapter do I require and if I need any additional accessors.What harness do i need to connect a Kenwood KDC-BT61U to an Audi TT MK1 with Bose system?there is almost never an adapter for an aftermarket radio to go to a factory amplified radio because the aftermarket radios higher powered outputs will burn out the amp and the speakers