When I had a 2.1 system, I used the Sunfire's built-in crossover. The single thing that made the transition seamless was the continuous phase control, but I had to use the crossover in order to accomplish that. You can also do this with physical placement, obviously, but that's not always an option, especially with WAF. For Maggies, if you go the active crossover route, a high-pass filter is a must. (My Sunfire had that, too, but maybe I took it for granted.) And you're also going to want high-quality DACs. MiniDSP seems to be the entry-level baseline, and they also have higher-quality options. I have zero experience with them, just playing meat proxy with Google AI.