I have seen some people treat the rear of the room around their surrounds when they used standard bookshelves, but I really don't think you need this sort of treatment.

As others have posted, take baby steps with any treatments: a carpet if you don't have one to treat cieling/floor reflections, something on the rear wall if it is close and flat, diffusion on the side walls if they are flat.

Fred

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Blujays1: Spending Fred's money one bottle at a time, no two... Oh crap!