Beautifully clear and smooth, and then the treble augments everything up the wazoo. Even if people are adverse to treble for that reason it's still worth a try if not for the absolutely polarizing experience of a hallmark phone intended for that particular sound signature. Just wonderful clarity. Everything technicality-wise is pretty good but gets overshadowed by the clarity. Definitely a strong love-it-or-hate it phone.
If under any other guise of perfection, the upper-mid and lower treble peaks would be unacceptable, but if you don't perceive it as a live-at-home-with phone and just accept the experience for what it is, it rewards you greatly. Also two peaks - very easy to EQ out, still very clear without them. I can't suspect the THD to be very high. I'd still try EQ even if one's adverse to that sort of stuff, just to understand how it is with and without.
Of course the asian/chinese earphone community gushes over them (those who have them) but then again they're trained to be resilent to all things treble I swear. This is one of those cases where I appreciate them too, but from a different perspective.
The build is aces, too. My first pair was a bit abrasive near where the cable enters the strain relief - but then again, that was an used unit.
Have you put them up against the all mighty and conquering K3K's though?