Robb, with both DPLII and Neo:6 the center channel level can be adjusted(you could of course configure the system in the receiver as no center if that's more convenient). I haven't studied the 659 manual for the specific numbers, which I'll let you do, but the center width adjustment which I mentioned for DPLII can adjust the center all the way down so that the mains handle all the front information(Neo:6 has a somewhat similar center image adjustment).
Again, keep in mind that there's nothing artificial added by this processing; the majority of sound in the concert hall reaches the listeners(unless they're conducting the orchestra) and microphones from reflected ambience which comes from directions other than the front. Processing such as DPLII, Logic 7 and Neo:6 detects the phase differences in these delayed reflections, extracts them from the front speakers, and steers them to the surrounds where they belong. The listening experience is made a bit closer to the original.
