If you want to spend even less take a look at the NI Audio 2 and EMU 0204.
No. In the last 4 years I have bought an M-Audio Fact Track Pro, a MOTU Ultralite Hybrid and an NI Audio 2. Next time it will be something from RME.
The D1 looks fine. Then again there is nothing it does that isn't done at least as well by the 2i4. Plus you get a whole raft of useful extra's in the package and the units both cost more or less the same. Separate volume controls for main out and headphones, Ability to cue, Quality inputs for recording anything. Balanced out option, Superb mixing and effects suite. On a value for money and potential upgradability terms it doesn't look like much of a contest.
No toslink on that one though. If you want to stay in the pro audio world you could try this:
a bit over $200.00 but has optical in (but no USB!). I had one for a while and it's nice, but runs hot.
The Audioengine D1 is probably the only one I've seen that has both toslink and usb. Currently I'm using a Motu and it's very nice as well. It has coax, usb, and firewire but no toslink in!
FSA Sptifre HD (if you want only a simple DAC)
not as good value as some pro device but , has everything you want ^^ and very compact .