Adding a sub and amp to Superb wagon

Hello all

I want to add a sub and amp to my Superb V6 wagon which has Columbus and the additional amp under the driver's seat already. Because of the electric seats there isn't enough height to fit it under the seats on top of the existing amp on drivers side or computer on passenger side. The only place I can think of is vertically in the cubby in the back on the driver's side. I want to keep the luggage area clear. Also, since I don't really want to cut into the loom leading to/from the existing amp unless I have to, is there a simple way to tap into the high or low level feeds at this point? I could pull the Columbus and connect into the back but then would have to route cables behind the dash and down under carpet. I haven't done that before and don't know how hard it would be. At least the power feed is easy with the battery in the rear, but I also need to get an on/off trigger lead through.

I have done a search but haven't turned up a lot that would help specifically.

Anyone able to help and perhaps got some experience with the Superb II, particularly with the factory amp loom?

Cheers

powerd