A tube output would have also been nice. 
Just out of curiosity...why?
The only reason I ask is that I recently did some testing with Peachtree's Nova. With 7 people in the room I played around bypassing the tube output and then adding it back into the mix and out of the 7 people in the room (8 if you count me) none of us knew when the tube was in use or not.
I just did the same thing yesterday with 4 people and again not one of them knew when the tube was in use or being bypassed.
I'm still floored as I wasn't expecting it but it really has me questioning a tube output on a DAC now.
Very interesting observations. Martin (Acid Jazz) and I have been modding an EE dac with with switchable output stages, one, solid state and the other a tube anode follower. Although its quite easy to instantly switch between outputs, the output levels are slightly different, and the louder always sounded better.
Luckily, my own dac has a slightly lower output than either, and the EE dac has a volume control that makes it easy to equalize volume between my dac and the EE, using either of its output stages. Matching the volume of the solid state output stage of the modded EE dac to that of my own dac, and switching between them in real time using the toggle switch on my CAT-SL1 to choose between the 2 line inputs, left us unable to differentiate between the two. This is not all that unexpected in that both modded dacs used the same opamp in their output stages. But the real surprise was that matching my dacs output level to that of the EE's tube output stage(with stock tube), also left us unable to differentiate between the two.
I don't know if assuming transitive equivalence is valid, but I do believe my system resolving enough and well sorted to be able to discern differences. Perhaps if the comparison was conducted with higher resolution source data (>16/44) the results might have been different. Yeah, I know Mike, I really should put that MTech dongle on line
......
FWIW,
Paul
