So.
First, consider I have no clue how to measure speakers. I just follow the instructions on the DIRAC manual.
Second, my room is shit. It is small (about 3.3 x 4.8 m with high ceiling at 3.3m), with masonry walls and my configuration is asymmetrical. Specifically the base configuration is with speakers along the LONG wall, and shifted to the left because I have doors to the right. So the left speaker is at about 1.2m from side wall.
I sit on a couch right against the back wall.
Speakers are about 2.3 m apart, 50cm from front wall, and 2.5m away from me. Toed in to basically point at my shoulders, but tilted up because they sit on the dedicated stands.
I challenge you to have a configuration worse than this. I also have a second configuration in which I move things around and put speakers along short wall, but I have not measured that one yet (it does measure much better).
So, a simple frequency response, uncorrected is below (U-mik at about 25cm from back wall):
View attachment 79797
The above is in stereo mode, with grilles OFF. As you can see the peak at 20k Hz is a tiny spec. The bump in the bass is accentuated by the back wall. If I simply lean forward, it is 50% less audible.
If you care about left and right speakers individually, here they are (left is green). Grilles are still OFF.
View attachment 79800
If you care about what difference it makes in my room with the grilles on, see below (black is with no grilles):
View attachment 79801
After a DIRAC filter plus some additional manual corrections (as Dirac is not perfect), I had a very decent result. The dip at 60 Hz and the one at 180Hz are still there, but that is physics isnt it).
FYI the measurements of the Revel M106 in the same exact position were not better than these in any way or measure. I can dig them out if there is interest.