Need suggestions for another pair of headphones (Have Sennheiser HD600)

Hej

Can anyone, who are familiar with the Sennheiser HD600, suggest a headphones slightly more open and with a wider soundstage then HD600?

I have tried Grado SR-325e, AKG K701 and K702. These three are far from my taste. Too much high midrange for me.
I also have Beyerdynamics T1, which I think is OK, but I tend mostly to choose my old HD600.

I though HD660s would be what I’m looking for, but they seems to have inferior treble compared to the HD600. At least that’s what I’ve read. I’ve never heard the HD660s myself.

Any suggestions in the same price range as the Sennheiser HD660s?
Has to be open back!