1991 nissan maxima w/ bose system

I bought a '91 Maxima and the harness is cut.  I have identified most of the wires using a DMM and the diagrams guide on this site (the diagram for the '89 Maxima is more accurate for my application than the '90/'91 posted).  I have three remaining wires left.  The unit powers up and retains memory, but there is no sound from the speakers.  Is there an amplifier?  Do I need to power it?  I can not seem to find any information as to a bypass harness, so I figured I could power the amplifier (if equipped).

Also, the speaker wires are a Belden type cable that has a wire shield around the conductors.  These wires tested for continuity to frame ground.  Should I do anything with the shields?  I have the shields taped back to their respective wire jackets at the moment.

Thanks in advance for any assistance!

OK...figured out the other three wires.  Amplifier, power antenna, and dimmer.  Connected the amplifier wire to the remote of the head unit.  Tunes started playing - sounded like garbage.  Rear speakers were distorted.  Front speakers worked fine, but then the right front stopped working after a couple of moments.

I'm taking this to the car audio forum...