Question about Beyerdynamic DT 900 PRO X

The sound is more balanced and clearer, the 990 has much more treble, but the sound is a bit better. It is even more comfortable than the 990 and has higher quality cable connections that do not break as quickly. The 900 is clearly a class above the 990 and it doesn't make much sense to compare them. It is more comparable with the 880.