Did you try this? It's a few posts about QX4's. I'm assuming you searched on Pathfinder
My guess is the speakers are amp'ed, so you'd need some type of line level or so adapter.
The second adapter, NISAH4N should allow you to plug a non-Bose system into a Bose (95-02 Nissan/Infiniti) car.
Here's some info for the 1997 thru 2000, but it doesn't appear to be for the Bose, you might be able to tell better than I could by looking at the pics.
Good Luck, and PM doesn't work. Is your old system a Bose in dash CD? I might be interested.