Have you considered trying a pair of different IC's
I have a kav 300 and use mit 330 cvt's with it and i hardly find it bright or harsh... If you get into a tube preamp, you will need to find a set of tubes as well that suits your needs sonically... I have an arc ls7 with my analog system that I have had 3 different sets of tubes in and it sounds different each time...
Try the IC's first, then look for a preamp...
Good luck,
Joe