Thanks for the info.
Well, your speaker positioning looks good (not to close to the boundaries). You're right, you DO have a lot of acoustic panels...maybe too many. But you said removing them made no difference (which they certain should make a difference). That right there tells me there is something wrong with the mic or the calibration of the sound card you're using to measure. Which soundcard did you use, and are you absolutely positive the calibration is solid?
Looking at Terry's calibration of his Behringer mic, that dropoff makes me wonder... In fact, it's the same dropoff that your measurements are showing. Terry's doesn't drop off like that, but it makes me wonder if your .cal file was working properly, thus the measured response followed that sharp downward slope.
Finally, have you experimented with more toe-in? Since you aren't sitting immediately on-axis of both speakers, there should be some natural roll-off in the HF's (typical in many rooms at that listening distance), but not that sharply. Just for kicks, try toeing them in so they point directly at your ears. Of course, don't do that until you've re-measured with your newly calibrated mic, as the mic may have been the problem and everything else will then be moot.
