bose acoustimass 10 series II outputs
 

Are the OUT- of the outputs connected in the subwoofer module?

Not really sure what you are asking but wire it up like this:
http://www.ecoustics.com/electronics...dio/488955.gif

I have to use a 7-wire multicable to connect the subwoofer module with the 2 front- and 2 backspeakers. So 1 wire is lacking and I want to combine the OUT- outputs of the backspeakers in one wire. Therefore I want to be sure that it's electrically possible. I could not find an internal diagram that clarifies this.