It's probably better to opt for a long run of speaker cable as opposed to a long interconnect. Monster does sell long single runs of their M351 subwoofer interconnect for subs with built-in amps. But since you have an outboard amp and crossover you should probably keep the monobrick closer to the pre/pro.
I've also read that placing a sub in the back run from the LFE output of the pre/pro doesn't always work well. I forgot why, but that's something you might want to look into. And that if you place the sub in the back it should be getting it's signal from the rear surround output. So I guess you would set the rear surrounds to "large" and use a crossover to split the signal between the rear surrounds and their subs.
I'm sure other more informed forum members can expound on the few points I bring up, or even rebutt them. I recall reading about this subject in Widescreen Review, Sound & Vision, and in this forum.
I've also read that placing a sub in the back run from the LFE output of the pre/pro doesn't always work well. I forgot why, but that's something you might want to look into. And that if you place the sub in the back it should be getting it's signal from the rear surround output. So I guess you would set the rear surrounds to "large" and use a crossover to split the signal between the rear surrounds and their subs.
I'm sure other more informed forum members can expound on the few points I bring up, or even rebutt them. I recall reading about this subject in Widescreen Review, Sound & Vision, and in this forum.