Hop on IRC and join the Neuros 3 design meeting:
http://open.neurostechnology.com/node/894
A full-featured DAP is being designed from the ground up, and as it stands the first run will have a case with a generous amount of room - it's conceivable that a digital out could be offered with test points that could be grabbed by a custom DAC and piped to a real line out.
Full disclosure: This device is going to be entirely community-designed, but manufactured by Neuros, the company I'm an intern with this summer. (Don't worry, they're great people.)
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Me on:
last.fm neuros
Gear: Revo 7.1 or Presonus FirePod -> HD650s.
Portable: Neuros III* -> Shure E4c.
Coming soon: Some kind of DAC -> tweaked PIMETA
* Not actually built yet, but a guy can dream, can't he?