Perhaps the reason Richard found no difference betwixt the different configurations is that the Bose PAS is a revolutionary product that doesn't neccessarily comply or conform to the limitations of previous or current technology, eg., Motion Sound, etc., etc. So it indeed may be possible to use just one Bose PAS setup and still achieve excellent results. The benefits of Stereo is of course the different effects that can be acheived that cannot be acheived with a Mono setup, eg., Pan, added ambience, and a true stereo effect.

Best regards,
Mike