My one remaining gripe with these speakers is part of the compromise EV had to make to create such a light cabinet. There is definitely a reason that many cabinets are made with 18-ply birch plywood, which is bloody heavy. I'm sure the panels on these PXM's is a fraction of that thickness, and probably MDF.
Anyway, there is some noticeable panel resonance that occurs, even at moderate volumes. I think the bottom is the primary culprit, since you can knock on it and hear a ring right around the area that I hear a boxiness in the response of the cabinet that is not present on my studio monitors...400Hz or so. There are also two side panels that rang pretty well when you struck them, too.
I quick trip to Home Despot to get some 3/8" dowel rod, and I fixed that issue.
Basically, I used a trick I've used on subwoofer cabinets I used to make, creating some scaffolding inside the speaker to counterbrace opposing panels and break up resonances...or at least push them higher in frequency and force a lot less amplitude.
I also added a little more batting in one corner. I'm very pleased with the results. I used to have to notch a bit at that 400Hz area, and now it sounds great without it. It seems to have a bit more oomph in the lows and low mids, too, but that could be imagination. In any case, it was a pretty easy modification with excellent results.