New DAC recommendation $1K, hopefully tube.

FWIW, I had the Benchmark and in my system, the Havana was better. I know people feel the Benchmark and Bel Canto sound similar, but in my system the Benchmark was just too analytical. The Bel Canto has better sound-staging, better bass, and is less diffused than the Havana in my system, but I kept the Havana because it does breath a special organic quality into the music that I want to hear sometimes. It's not goopy or syrupy, but isn't hyper-detailed.

Without getting too technical, the airport express does exhibit a fair amount of jitter, and the Havana's strong-point isn't jitter reduction; it also doesn't have balanced outputs and it's digital input selection is limited. That being said, I have one (in addition to a Bel Canto DAC3) and love it. I'm running it from a Mac Mini and use the Bel Canto USB link (although there are many usb to spdif converters) to go from usb to spdif in the Havana. In general, i don't think airport express is the way to go for a server setup, unless it's for more casual listening. If you can find a used havana and get a good usb to spdif converter, it will keep it around 1000. The biggest difference, no matter what DAC you get, could be getting away from the airport express.