I essentially want to do the same style setup. I got your message about a crossover too. What if the amps running the speakers had a built in cossover? i was thinking about taking out a 4 channel and just using one to power front and back mids and then run the tweeters off the same line as the mids but just put a passive crossover (I think that's it, I'm still reading) before it. I'd still end up splitting the sub line though and if I ran one 4 ch for the other speakers I'd have to be able to put the front and rear lines in or else I'd just have an extra spot not used from my sound card. Then I might as well just get a more basic sound card. I'd just be down grading alot to do all that. You know what I mean?