How to match amp with pre-amp

I have BW Nautilus 804's with a Classe CA300 amp. I am looking for a good pre-amp, but don't know where to start, what to look for, etc. I am currently using a Harmon Kardon receiver as a pre-amp and have auditioned a Forte pre-amp. The dealer wants a grand for the Forte but I see no difference between it and the receiver, so needless to say, I'm not dropping a dime on this. Any advice would be appreciated.
Get the matching premp for your amp and you will have magic. There is very good synergy between classe products
Classe matches very well with Conrad Johnson preamps, if you are considering tubes. The Classe CP50 is a nice full featured linestage, but does have a slight hum from the power supply. The 47.5 power supply is quiet, but in my opinion, it is a step down.