I am reinterested in these. I think a comparison to a shure 1540 is in order.
Sorry but the best I can do is compare them to the Shure open back 1840's. Briefly: the Nighthawks reach greater depth in the bass than the Shures...and more powerfully. When the bass viol is moving in the deep bass the Nighthawks articulate the movements clearly...no boominess. The Shures are accurate and pretty good, but no match for the NH's!
The mids of both are excellent so the voices of male and female singers are rich and forward...the NH's though have the edge here too. Both of these headphones love to pllay jazz and classical music. The Shures really are in their glory with trios and string quartets,while the NH's encompass that area too, but go beyond and handle the many instruments of the symphony orchestra with greater aplomb than the Shures. Both are excellent really.
The highs and altissimo range, the Shures are good, but the NH's are better. Smoother, more detailed even when violins play intricate passages near the peak of their highs, the sizzle of cymbals is crisper, the sound of guitarists nails on the strings are absolutely clearly articulated, the banks of first and second violin sections are beautifully reproduced by both, yet here again the Nh's for me seem to handle this even better. Less edginess to the registers above high C. both do justice to the warmth of the cellos and the deep woody textures of those beautiful instruments. The double basses are best handled by the NH's, but the Shures are no slouches either.
The sound stage of the AudioQuests is wider and deeper but not by too much. The Shures once again are pretty darn good.The Shure's are a little drier than the NH's IMHO and somehow make my music slightly less enjoyable than do the Nighthawks.
In sum, both are made to play jazz and classical music, if one must play rock and that sort, the NH's would do better if for no other reason than their fine bass, but they are not happy doing i think...metaphorically.speaking!
Sorry, too much for me to do any more clearly. Hope this helps you or anyone.
Leo