Agreed, it's unlikely to be the speakers. It sounds like there is something causing some kind of response curve in the signal processing stage. I don't think its the room, especially after the treatments. Try a different source, a different processor, and a different amplifier. The problem sounds like its somewhere in that chain.
I think the problem almost certainly is the speakers. I think that the OP has become a much more critical listener. I think the vast majority of males, but not females become accustomed to the sound of their systems and on the whole satisfied. There are some, and especially women, that become more and more dissatisfied with their systems to the point where they find them very irritating. Since I think this is especially true for women, I think it a definite factor in WAF and a definite reason why this hobby has such a male predominance even with a leveling taking place in so many other spheres.
I know you did an thorough review of those Klipsch speakers Shady, but you did identify what are in my view serious shortcomings.
First the listening window is far too narrow. There is much data to show that narrow dispersion is not a preferred characteristic of speakers. Its relatively narrow dispersion window will not endear them to many listeners.
I think your data shows that there is likely serious issues at crossover. That dip and deep null is I suspect an indication of serious phasing issues at crossover. I know the wisdom in many quarters has been that these issues are not serious. I vehemently, along with quite a few others believe these issues to be serious shortcomings.
This is compounded by the fact that in my view the crossover is at a terrible frequency. At 1750 Hz this is a region where many are highly sensitive to aberrations especially crossover issues. I avoid crossing over in this band at all costs. The crossover would have to be just about 100% perfect not to cause audible problems for many. This crossover as you can see from your data is far from perfect and I strongly suspect an audible issue.
So I suspect this OP is one of those individuals who requires speakers with a very smooth midband response including the off axis response.
Clearly your data show that these speakers are far from the worst, and have a lot of good attributes. However for some, and I think the OP is one, they fall short.
If you think this is a roundabout way is saying that I think the OP has expensive tastes, then I think that is a reasonable conclusion.