I cant agree with that, I think the HD560s is in nearly everything better than the HD660s. The Hd560s has bigger soundstage, better imaging and better bass extension and sounds overall way more correct/neutral to my ears. The build quality and comfort are better on the HD660s tho.

I love the HD660s for movies, podcasts, videos, everything thats vocal focused. It has a kinda warm/neutral tuning that is just easy to listen to.

But for music and especially gaming i prefer the hd560s. The hd560s has so much better soundstage, imaging and depth perception than the hd660s, its not even close. The HD660s can image very well but its small stage and relaxed treble make it quite bad for gaming, especially if a lot of things are happening at the same time.