While I haven't seen impressions of the DarkVoice specifically, I do remember that the overwhelming opinion of using the X00s on tubes was that it resulted in an exaggerated lack of bass control.
I think its more the design of the tube amp, the DarkVoice being OTL would not match up with low z headphones but hybrids like the Lyr2, Liquid Glass would probably work quite well. I'm still waiting for my TH-X00 but have a TH-600 and they sound really nice on my Ember and Lyr2, a little bright on my Asgard2.