Brightness/harshness is often caused by poor speaker positioning in relation to the listener. The distance from the walls, the distance between the speakers, the distance from the speakers to the listener, speaker height, toe-in and tilt can all cause brightness. Depending on the size of your room, you may not be able to accomplish a perfect setup, but I've found that small things like reducing the amount of toe-in and or tilting the speaker back slightly can reduce harshness.
Here's a good summary of things to try.
http://www.gcaudio.com/resources/howtos/speakerplacement.html
Here's a good summary of things to try.
http://www.gcaudio.com/resources/howtos/speakerplacement.html