So it seems you are looking for an ambient/layered soundstage image. You are wanting an overall warm balanced sound. With good bass detail resolution, yet not excessively bass bloated. I think you should throw away the word "dark". Its just too vague, and open ended of a term to base a detailed discussion around... IMHO of course.
The HD650 meets most of those criteria, although I find its bass flavor to be more "resonant" than dry / articulate. I think the 650 definitely adds a sense of harmonic-resonance below ~80 Hz, it makes up the bottom half of the "veil" everyone talks about. The top half being its smoothly recessed upper midrange. I have heard others call the HD650 bass sloppy and unrefined... I for one wouldn't totally disagree with that.
I think the DT880 could be an option for you. Its definitely what I would consider an "airy" sounding headphone. It has some treble boost above the upper mids that adds to its overall presentation. Bass response is its strong suit. Articulate, detailed, deep-extending... Awesome. Its also no slouch with the imaging and soundstage too.
The Q701 is a must consider for you too I think. Of the 3 it has the best image and soundstage layering. Bass is plentiful, articulate, deep and detail-rich.
Edited by kramer5150 - 5/14/14 at 9:03am