You might try the Apogee MiniDAC. It is about $1,000 and can take the optical feed from the Airport Express. I used it extensively and it sounds absolutely beautiful, although it would drop the USB connection occasionally.
In my experience, if done correctly, PC audio can sound every bit as good as (sometimes better than) a high end transport. Remember that these days most CDs are mastered on computers.
In my experience, if done correctly, PC audio can sound every bit as good as (sometimes better than) a high end transport. Remember that these days most CDs are mastered on computers.