Point of curiosity, Mo; you commented that the 69dB level used "about 1 watt". You may have been just using a ballpark number, but it would seem that less than a tenth of a watt would actually be used at that level.
Wonder if suckouts due to room surface interaction affected some of the observations. For example, both published anechoic measurements and my own measurements/listening indicate that the M22 is exceptionally flat(for a speaker)and full in the upper bass/midrange area. Also, Alan has pointed out more than once(this may be what Ken was referring to earlier)the great difficulty in distinguishing between the M22/M60/M80 above the low bass in blind listening tests.
Yes, when set in the all-channel stereo mode the left side surround and back surround channels duplicate the front left, and similarly for the right side channels.
