Just now listening to HE-400 after Q701. HE-400 are "more fun," greater sense of drama, but sounds like listening to media rather than getting lost in it and immersed like "being there" in the musician's fantasy. A very good headphone, overall they are close for quality, but side by side I prefer the Q's despite new toy syndrome.
Very first impressions tho.
I can see where you might like the 400s better. Lots of bass, sparkly treble. Yep - give it a few hours on the head. IMO that bass starts to be overwhelming and that treble becomes an icepick to your skull. Never that with the Qs..