After a year or so fooling around with two large ASC picture panels i finally mounted them on a "secondary" wall solely for WAF factor. This wall is in offset in front of one speaker about 12 feet.
Low and behold, it has "solved" my brightness high frequency issues 90 percent. After swapping a lot of gear and cables, i can state with full authority that the room first doctrine is the way to go.
I have always thought the panels would work much better either directly behind my listening position, or on a long untreated side wall, but this is not the case in my windowed apartment. Go figure.
In addition to my comments above i would strongly suggest one explore panels of this type before adjusting equipment. The acoustic forum has a bunch of active room acoustic makers like GIK or Real Traps.
I also recommend the above stated picture panels. I used some B&W shots from an up and coming nyc photographer and they came out much better then expected.