powered front speakers

I have just joined the outlaw community two weeks ago with 950/770. I am using an old pair of Polk SDAII (full range with 10" passive woofers) along with Aperion 5.1 speakers (a sub and 5 bookcase speakers). I am very happy with the current set up especially with 770 powering the Aperion surrounds. Their high are still crisp and clear but they are more mellow like a wine that is aged just right to take the edge off the tannin. They are a little weak in the low mids -- thus my full fronts. Aperion just came out with powered towers (8" woofer with 150W amp). My question is how would the built in subs in the front speakers work with a separate sub (12" woofer with 250W amp)? Where would the third one go? Right now, it's off to the side just behind the right surround speaker. My room is 24'x14" but I cannot place the sub anywhere in the middle of the room. I do like the idea of having sonically matched speakers, though. Should I get these speakers?

usually one would use the front channel pre-out and connect it to the sub input of the corresponding front. making sure to set crossovers accordingly. alternatively you could use the sub pre-out to do all three. the first way is probably going to be a lot better, as a standalone sub is usually better than any in a powered tower...

I'd have to agree on this one. At my workplace we had (at one time) the Athena sets that included powered subs for every channel. Testing both ways with various crossover points, myself and a couple of my coworkers came to the conclusion that the sound was more solid using the channel preouts to the channel subs and the dedicated LFE preout to a standalone sub. Using all channels for LFE was tremendous for movies, but for music, the sound was a little thin without the subs on each channel.