Hi Dustin - Your system looks great. As far as the soundstage issue goes, have you taken independent nearfield measurements of the two speakers with a spl meter? If they measure differently, that's probably your answer. If they measure the same, it could be an effect of your room. Does your room have any significant asymmetries?
Integrating your sub into your system is tricky. Using an external analog crossover will certainly work, but you should choose carefully because, IME, many crossovers can dramatically diminish sound quality. The good ones seem to be crazy expensive, and I know you just spent a lot on your speakers and sub. I would search the A'gon archives, or perhaps create a thread asking for advice about high quality but affordable crossovers.
