20 watts may be shortchanging nearly any bookshelf speaker except very high sensitivity ones, and those would be large. That amp may be OK for desktop system, but not something that could fill the room. I would encourage you to get a real amplifier. 50 to 70 watts should be better. You said you were looking at the RR2160, why not just get that?
As for bass management, it is pretty beneficial. It saves the speaker from playing in the most difficult frequency range, and it can prevent a lot of distortion. I would really try to find a way to get a system that has bass management, especially when you are looking at such good subwoofers and speakers.
If you are looking at the RR22160, the Ultra-X12, and the BLSv2, I would call Outlaw up and see if they can give you a discount for a package order like that. They may be willing to shave a few bucks off that kind of order.