Steve, the surround placement can't be optimized for both rows, so one plan is to optimize for the first row(e.g., about 3' behind)and have guests you don't really like all that much sitting in the second row.

I'd think that putting the surrounds directly to the side of the second row(i.e., about 5' behind the first row)would be a pretty good compromise.

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Enjoy the music, not the equipment.