2x Genelec 1029 (flush mounted in frontwall) + 1x Genelec 1091 Subwoofer (free standing middle of frontwall. When I measure the frequency response of 1 1029 + subwoofer I get a -+3..5dB variation in the frequency response (either left or right side). The microphone I use (Behringer ECM8000) is omnidirectional and is directed to the corrospondind box (approx.in height of the loudspeaker).
If I finally turn on both or better said all 3 boxes (Subwoofer incl.) the frequency response had strong dips and is no longer in the +-3..5dB scale. I guess comb filter etc. are the reason for this.
The question is now: What is the right procedure to measure a room? First lets say the left box then the right one and that's it if everything is ok with the single boxes? Or do you finally also have to measure the response of all speakers on?