I used to use stand alone pre-amps. But today I just use higher performance receivers as a pre-amp. I use external amplifiers of course. The unit I have used for a while now in my 2 channel system is the Yamaha RX-V2600. You should be able to get similar pre-amp performance fro the RX-V1800, which you can get factory refurbished for about $450-$500 on eBay. Gene here at Audioholics measured the pre-amp section of the RX-V2600 and found it performs as well as, and better than some stand alone pre-amps. He uses an industry standard Audio Precision analyzer if memory serves. That is why I chose that specific unit, and I could not be happier with it. I believe the RX-V1800 uses the same pre-amp section, as well as the newer RX-V2700 and RX-V2800. Really, only the HDMI capabilities and video/audio decoding features are different on the newer units, but I only use it for music so I really have no care about those things. I did hook up a small portable television to the receiver video outputs when I set initially set it up so that I could navigate the GUI and make sure everything was set to 'flat' and no sound processing was engaged. But after that, there is no need for the video monitor.
I do recommend placing some spacers between the receiver and any components set on top of it if you set anything on top of that. The above picture shows my CD changer directly on top, but I later placed a 1.5" clearance stand between the receiver and player to allow proper ventilation.
-Chris