We do have a tube DAC in the works. It does have optical input and output, and will also have coax input and output in the final iteration. It's still in development so I can't really give a firm time frame for it. I'm guessing that maybe at the end of the year/early next year we may have a production prototype ready. The DAC is really intended to be used with a soundcard that has a SPDIF input so the DAC can send its clock to the soundcard, but we have found that it works nicely just hooked to the SPDIF output of a CD or DVD player too, without reclocking.
Sorry to go off-topic a little here, but THAT IS SO AWESOME I'M EXCITED.