Have you tried repositioning your speakers? As previous poster had implied with suggesting the room correction devices, your room has more influences in the way your whole system sounds than changing any part of your amplification chain, IMHO. It is my belief that properly positioned average speaker system will sound better than the top end speakers in a poor room, improperly positioned.
Before you give up on the speakers, try moving them out away from your walls.
Before you give up on the speakers, try moving them out away from your walls.