There's a good comparison article at the Secrets of Home Theater sight. I don't have their http, but I would do a search to get the sight and read it. It compares DPLII with Circle Surround, Logic 7, and DTS-ES. Briefly I recall the best results was achieved by DPL II and Logic 7.
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ONCE, I CONSIDERED SPARING YOUR RETCHED LITTLE PLANET CYBERTRON, NOW.., YOU SHALL WITNESS IT'S
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I've heard them all, and Circle Surround sounded the most artificial and limited-range of the bunch. DPL-II is definitely the most natural sounding, though Logic 7 is pretty damned close.