This 668b has ear friendly treble which is more comfortable than Fidelio X2.
X2's treble lives between on the border of shrilling that gives more sound stage and more resolving ability without congestion in the complex passage.
668b's treble is well within safety zone but when it passes through complex outburst of orchestration I feel some degree of congestion onto upper side.
But those situations are not everyday business.
Whenever I wear this phone, my desire for upgrading phone is quenched.
I consider this phone would have 90% of my possible upgraded sonic quality.
Also it makes me smile for multiple reasons which is not only the cost, but also SQ, my self-content or self-control keeping out my temptation, etc.
How I got back down to 668b from high end planar phones in the past? it should be amazing story.
Are you using stock pads?