Hey Zenieth- what did you end up doing? Audioman4 gave you some great advice, what with the Needle Doctor recomendation and all. Personally, I've got it good 'cuz Jerry Raskin himself helped me out when my old Adcom system (since replaced) needed similar help. I had a GFA555II (?) a few years ago, and hated the sound from the internal phono preamp. You could actually hear the fuzz and static come out of the speakers when you turned it to the phono input (and don't bother turning it up, either!) I sent it to Adcom to have the phono section jumped out, and then I visited the good doctor at his shop (I'm local). He damn near talked my ear off, but I learned a hell of a lot! When all was said and done, I left with a dedicated phono preamp that is easily adjustable for different stylus', didn't cost an arm and a leg, is dead quiet, and fits my system. For your Adcom setup, which is better than mine was, you could get very good results with a seperate phono preamp, and you don't have to pay alot to get great sound.
I can't recommend Jerry Raskin/ The Needle Doctor highly enough. If you still haven't done anything, or are still just thinking, check him out.
'Nuff said.