Doug, Bruce is correct: the two rear-center speakers play as one, with a single DPL output split with a Y-connector. The speakers I use as the rear-center 'one' are a pair of Def Tech BP-20s, which are very capable stand-alone towers, basically the same as my mains (BP-2000s) without the built-in powered subs.

They only stand about three feet apart, so I'm not going for any separation here, anyway. They do provide all the bass I could want from the rear, with the DPL set to 'L & R - small' and 'center - large'.

The surround speakers (my sides), the BP-Xs, are di-polar, as are all except the front-center, but these are the only ones that do not have the driver panels opposite and parallel.

They are trapezoid-shaped, with the wide back panel against the wall, the narrow front panel blank, and a pair of 'woofers' and one tweeter on each of the angled faces, so they do fire in a splayed direction, to the front and rear of straight into the seating position.

The fact that the two panels of drivers are wired in phase is what makes them bi-polar, as opposed to di-polar. As I've said before, I believe that once we graduated past a single surround channel, a la Dolby Surround & Pro Logic, the benefits of de-correlation vanished, and directional cues became more desirable.

Larry
www.fineelectricco.com