upstateguy, your impressions are really interesting to me because I am considering this DAC. I want to use it with USB, and pair it with HD600's. Am I going to need to pair it with an amp that brightens the system up? I guess that's how I interpret your comments.
The Stello HP100 has the "filter selector", and I was considering that would be a very handy way to compensate for this. Can anyone comment on that combination?
You won't go wrong with the Stello DA100, it does a very good job with all three of the amps I had it connected to, the Woo3, M^3, and GS-1. It is certainly better than my Constantine USB, Zhaolu D2 and DAC-AH.... and a good value at its price point.
I'm not so sure about the HP100 though. What other amps are you considering?