dual centers is a bad idea, if you want the sound to come from below the tv, then put the center speaker into the "riser", on a shelf underneath it. however if the speaker seems to have a position now it will continue to do so.

two speakers for center is a bad idea, because voices come out of them. no 2 speakers are identical, so they will never be the same sound exactly. plus splitting the signal degrades it. the point of a center is to anchor the dialog to the image, if the centers are on the sides then they are really nothing more than mains in close proximity to the screen. plus two speakers will push the sound out in different places, with a void in the middle if they are perpendicular to tv or interfering with each other if they are angled toward seating area. i have my center on top of my 65 rptv, and have no problem with dialog seeming unnatural. the center is only slightly smaller than the width of my tv, so i presume that helps...
there are just a lot of negatives as far as having two centers, if that was ideal then that is what we would all have, 8.1. yeah they could be fine, etc., but just buy one that is twice as good as the two...

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