I have the DT880 '05 which isn't as linear as the DT880 '03.
The DT880 '03 is the better allrounder, but, on some songs the DT880 '05 just "SINGS". That's why I still have it.
The DT880 Pro is one I don't know about, as I haven't heard it, but from what I understand, it's similar the the DT880 '03.
YMMV, as usual.
I like the HD600 more.