The HE-560 was supposed to be a combination of the HE-500 and the HE-6, but I don't hear the meaty/thick notes that I heard with the HE-500 or the HE-6. IMO, they sound much more thin, with a lot of air. I have had them on burn in since I got them, and they haven't changed. I think even the HE-400 and HE-4 had a thicker sound than I am hearing with the HE-560....they remind me more of the Beyer T1, that I had twice, previously. The mids and treble are clear, leaning on the bright side. This is from my tube amp and 5wpc. This has me interested in the HE-400i, the impressions from the Chicago show paints a picture of them as a HP somewhere between the HE-500 and HE-6!
I do love the clear details and brighter airy sound......using the same cable on the Rev.1 and Ref.2, the preorder Rev.1, with their pads have slightly less clarity and air in the mids and treble to my ears.
I would have described the previous 560 as having a thick midrange, for me anyways... The current one, not so much :p The 400i is thicker and has a larger body compared to the 560 (both models).