[joelpearce]

Depending on how your layout is set up, I've actually had excellent results from my Mackie 402-VLZ3 mixing board, and it was quite cheap.  They drive the 600 ohm Beyers with no trouble, they are quite cheap, and they are made with the same parts that Mackie uses in their larger mixer boards.  With multiple inputs and outputs, it also gives you some flexibility when building a setup around speakers and headphones.