Gmc56...as is typical of Agon :-), you ask a question and you will get 16 responses with 16 different suggestions. While an issue like "excessive brightness" can be caused by many different things, I suspect there are a few things from this list you want to try first. Eventhough, I suggested speaker toe-in and room treatments as a first attempt, having read through all of the suggestions, if I were you, I would try Duke's (or Audiokinesis') recommendations first, given his knowledge of speakers and their interactions with rooms. Many speaker designers use felt inserts around the tweeter in their designs to tame brightness, so his suggestion of buying an after-market felt product that you can fit around your tweeter seems eminently reasonable to me. You should check out the link he provided. His other suggestion of finding a point in the vertical plane (where your ears are relative to the tweeter that is) where the sound is not as bright is also an easy and cheap way of finding a fix. The fix will incorporate finding seating that either has adjustable height or is fixed at the height where the sound presentation is no longer bright. The seating height fix by the way can also be found in Jim Smith's book, "Getting Better Sound," which is probably one of the most cost effective investments to enhance system performance (no affiliation with him just a satisfied customer). If the felt and seating height adjustments don't cure your problem, then treating your room, changing cabling, and ultimately changing speakers (suggestions for soft domed tweeter are not off the mark in this respect)are the way to go. Good luck and let us know how it works out for you.
