As a reference, I like the sound of Momentum over ear.  I don't like Grado Sr80i which is too bright for me.    Comfort:  Excellent.  I worried the headband design will not be comfortable but after a week of using X2, I think this is probably the best system for such a large and relatively heavy headphone.  Unlike the usual headband design, the weight of the headphone is evenly distributed on the head. I don't feel the headphone being heavy at all. There is virtually no or very little clamping force and yet the headphone is very secure.  Momentum...