I just found a second-hand DT901 Beyerdynamic and I am quite surprised.
Besides the fact that nowadays is a collector's item, his musicality is more enjoyable.
Actually the sound balance is well done, low and high and medium slightly increased a little digging. The accuracy, dynamic stereo are waiting for you. Short little fault his side. Only the extreme bass and treble are a little lack of extension, but it works well like that and wear may be passed by.
I would even say that I prefer the DT911 and 931.
The comfort is like the pre-cited headphones and 990pro, not fatiguing, and open too.
The headband and pads were changed because they have outlived their usefulness.
If like me you find in good condition, please, to 95 € fpc (in my case) it's worth it.