I agree what you're saying about speakers. Sennheiser makes great headphones all around, the HD570 and HD590 are just the anomalies. But their sound signatures can be all over the place, the HD650 and HD800 which were or are both flagships sound nothing alike.
The HD580/HD600HD/650 are good headphones and not like the Dr Dre headphones.
It has been a while since I heard the HD595 and I sold them pretty quickly, but I don't think they were that bad either.