Jerry use two seperate outs L/R for stereo...chain the using the Bose aux out for mono.......or use two Bose hooked to L/R main outs on your mixer & hook the powered 15" speaker or sub(s) to the sub outs on the mixer to have a seperate Vol control.
A small mackie mixer like this should fit your needs...
http://www.mackie.com/home/showimage.html?u=/products/802vlz3/photos/802VLZ3.jpg [This message has been edited by Dnj (edited 10-04-2009).]