Wid... I won't go so far as to say that was an erratic response... the average anechoic response was about +/- 4 dB ... And I think the M-80 as it exists today is a lot flatter... The M-80 has 6 drivers along a 39 inch or one meter (roughly) line array... getting a smooth response at 2 meters (less than 7 feet) would be tough.

An open question... All M-80 owners sitting 6.5 feet from your speakers please speak up ...