The Quad 99 CDP CD Player (not the older non-CDP version) is excellent for the used price. It has 6 digital inputs and it also has an excellent built-in analog volume control. If you have an all digital system, you can connect the Quad directly to a power amp and forget about an expensive pre-amp.
I've owned the Quad and several other CD players with digital inputs (including one of the ones mentioned above) and I can tell you, the Quad is a great bargain and only gets outperformed by CD players costing a lot more money (at least 2-3X more IMHO).
Enjoy,
TIC