Aftermarket Stereo Help

[brownoutbacxt]

bought a 2009 outback xt with a non-working stereo, the controls work, but no sound will come. which is an issue because I know very little about stereo wiring. I am the third owner, and was told that the first owner started to install new stereo components, but never finished before selling the car. so basically, there is a whole mess of wires running to an aftermarket amp under the passenger seat. also the sub in the cargo bay is gone.

 

I tried to connect it with no luck, later tested the wires for any power and they all were dead, figured its not connected. so I traced them up through the center console and found more wires under the drivers seat, also dead. then I opened up the dash and found the head unit has the completely stock wiring coming out of it.

 

so my question is: is it possible the wires are connected elsewhere? to some sort of umbilical chord? or am I missing something? are stereo wires even supposed to have power? any help on where to even start would be greatly appreciated because like a said, I don't know much.