Updated impressions. Last ones for the day.
As of now, I have 10 headphones on my desk. I wanted to do a quick sampling of each one just to get a better feeling for all of their sounds compared to each other and also my more established pairs. The D600 was the last pair of the rotation. To my surprise, they actually have the most amount of treble compared to everything else I've got at the moment. Definitely, without a doubt, it's sound signature is reminiscent to the D2000 and Pro 900. I'd say perhaps the bass of the Pro 900 and the mids and treble of the D2000. Beyond that, I find it pretty interesting at how different these sound after listening to everything else I've got. From now compared to my out-of-box impression, bass doesn't seem AS bad anymore (yet still too much), but midrange and treble are definitely worse than before. Bass is still pretty annoying with anything that isn't specifically dedicated to bass, and the midrange/treble can mess up some vocals (sounds a bit shallow/thin and has a zing to it). Treble does indeed have sibilance on some songs. Overall, better than the XB700? Um, I'd actually take the XB700 instead, even though it's not quite as "advanced" sounding. I like the presentation of the XB700's treble far more than the D600, as it's not fatiguing and the vocals have proper weight to them. NOTE, while at one time I was a huge fan of the D2000 and Pro 900, my most recent pairs of both were a major let down due to my significant change in preference to sound signature. I simply don't like V-shaped sound anymore, and the D600 is exactly that. So perhaps it would be best to take users with more credibility in the art of this sound more seriously than me, because quite apparently, I'm not a fan. Glad that has been firmly confirmed now.
I'll make comments is anyone asks, but I won't post further impressions. I'm out. I'm forgetting this is an appreciation thread and not a discussion thread.
Fans of the old series, I'm quite certain you'll be pleased.