Phil,
Did you check out the SRH940 or SRH840's? Impedance is 42 and 44 ohms respectively??? So honestly I am not Shure
how good these are going to sound, but they are getting good reviews. They have my curiosity peaked.
Also both these are closed back compared to the open structure of the Sennheiser HD650 you reference. I have always liked the separation of a closed back can.
Michael