I think that the treble on DXP is on another level, much more energetic, more life, more uplifting
Signature DJ is smooth and not as well expressed in the treble, reminds of some smoother ultrasones like DJ One Pro, while DXP has both an excellent bass and an excellent treble, it is much more of an all-rounder for me.
I am not sure about detail and clarity itself, but the detail revealing or rather how much the detail is expressed is better on DXP. Not sure if this makes sense, but it is possible to have a lot of detail but have it blended with the background, and it is also possible to have slightly less detail, but more expressed, especially like DXP which has the detail revealing abilities top notch