Drew, if you have enough room behind your listening position(say 4' or more)for back speakers to create a back surround effect, then it'd be better to use the full 7.1 setup rather than 6.1. THX, Dolby and other authorities suggest using two back speakers even if they were playing the same mono material, mainly because of a psychoacoustic effect in which a sound produced by one speaker directly behind the listener can "reverse" and appear to come from directly in front rather than behind as intended. Also, when DPLIIx or Logic 7 is used with either two channel or five channel material, the extracted sound is sent as different "stereo" signals to each of the two back speakers. The lack of any 7.1 material therefore isn't a reason not to have a 7.1 speaker setup.
