Mulviling and ghdprentice hit the nail on the head. A good preamp is so important. I don't mind a little coloration but a nice preamp adds body and texture. I've tried a couple times without a pre and the music was analytical and boring. I don't care what anyone says there is nothing like a good preamp in your system. A former friend of mine argued until he was blue I was wrong. I kept laughing and said you will not convince me because I know better.
I wish I could remember who wrote a review on preamps in a system but they unequivocally stress they are very beneficial.