A good 2ch preamp?

OK....I've been a home-theater nut for 8 years...always buying mid to high-end home theater equipment....but it has always lacked something on 2 channel audio...well the wife said I could rebuild the basement and I'm thinking of a room dedicated to 2 channel audio...Its going to cost me quite abit in the remodel ...so I will be limited in funds....now I can buy a mid-priced preamp (300-500 dollars) or I can buy a used high-end preamp....in the same price range...but I have no clue where to start or what to buy...I've been looking at the pioneer elite preamps on ebay..(c-72,c-90,and the c-91)...are these decent preamps?....the amp I have is a yamaha m-80...and info or suggestions would be great...chris