I have the D900 from 1989 and the current D7200. The D900 are very nice headphones, confortable (with modern earpads), excellent sound and bass. They were my favourite together with the open back Sennheiser HD599. Nevertheles, since I bought the D7200 I barely use the old ones any more. Sound detail and tuning is much better in the D7200. I have very limited experience but the D7200 are my absolute favorite headphones nowadays and they are incomparably better than the other two. I cannot compare with the 5200 and 9200. I wish I could try them!