You will get more improvement for your dollar by upgrading your pre-amp. With your budget constraints I would purchase a conrad johnson PV-10 pre-amp (tube). You can find them used on audiogon and e-bay for around $600. Tube front end and solid state back end is a wonderful combination.
Thanks for advice on smooth amp!
I wanted to thank everyone who checked in with their opinions on what I should do to smooth my system out. I realize that there is much more to think about than just the amp! Unfortunately being on a grad student's budget severely limits my ability to make changes (and I failed to mention my budget limits in my previous post). That being said, I may consider trying out a new CD-only front end, as this, ostensibly, is the weak link in my system. Perhaps a new player, as DAC's tend to be more expensive I think. We shall see... Again, thanks to everyone for helping me out! djjp