fostex full rang p1000k

Hey! Just wondering if it would be possible to improve the sound of the woofers, the base is good, but the high tones are flat. Maybe iam asking to much from these drivers?
I've tried many types of amps with the same results.
http:// http://www.fostexinternational.com/docs/speaker_components/PSeries.shtml
I do use these drivers in a small room, but not near field.  thx