If you like the hyped bass of the Ultrasone pro 900 then go with them.
I have a pair and they're perfect for electronic music/hip-hop/rock, but I think for classic music there're much better cans out there. Maybe some Sennheiser HD-650 or AKG 702.
I would try a few before purchasing them.Iit's always a question of your personal taste when it comes toheadphones, the same counts for monitors as well.
Personally I would start trying out with the above mentioned AKG and Sennheiser models