Thanks for all the info.Will I need a preamp for this?No, not with your Wadia 850. However, you will need a digital input, which was apparently optional on the 850. If yours doesn't have it, perhaps Wadia can install one.
You would configure the system as follows:
Hard drive -> Squeezebox (or the like) -> CDP with digital input -> amplifier -> speakers.
We have over 800 CDs on a hard drive, and are about to jump to a drive that will hold over 2000 CDs. The Squeezebox will read the files wirelessly, so the hard drive doesn't even have to be in the same room. In fact, ours is connected to a computer down the hall, making it possible to change the playlist or volume with either the Squeezebox remote or at the computer. You simply download the free software at www.slimdevices.com (click "Downloads"), and you can view your entire music library, change playlists, volume, etc. from the computer, whether it is in the listening room or not. The convenience is unbeatable, and the sound quality outstanding, provided you have a good DAC. The DAC inside the Squeezebox is passable, but nowhere near the sound quality of your Wadia.