Gonna wait for final judgements but it seems like it shares many of the HD 650 traits. smooth, not prone to sibilance whatsoever. Running the infamous R.E.M automatic for the people for example it´s hardly portraying sibilance at all in any of the GMPs. Yet I don´t feel like I am loosing that much detail otherwise as from the HD 650. I don´t own that anymore but it doesn´t sound quite as dark from my memory. Or my preferences have changed . Laid back, surely nothing that gets your head bumping. Relaxed headphones that feels a bit slow but have it´s own nice rhytm. Like waggle you to sleep. They truly never upset you anyway except for the soundstage not being up to par with the K701 or Pro 900 for example also on the 400.
"Kinda HD 650 in some way, more smooth sound than DT 770, a pleasant for sure. All-in-all a headphone with no visible flaws, very natural sounding, much better than hyped Denons, etc. "
I can't tell, because I never listened to a HD650....