The bass decay time below 50Hz doesn't really matter too much. The wavelengths of those frequencies have an inherently long duration. That curve is very choppy though, it is almost as if there is some kind of comb-filtering, like there is a phase conflict. You need to make sure everything is playing together in phase.\n\nThat is good, but the Y-axis is still a bit wide. Limit the top of the Y-axis to 95dB.\n\nPossibly the Fireplace reflections. It extends 2'9"x6'1" into the room floor to ceiling about 5'6" in front of the right speaker. My seating position is about 10' off of the back wall the 2.7s are about 34" off the front wall. It could be reflective wave cancellation from the rear wave reflected off the front wall.