I have not heard anything like this before, they were quite allright out of the box except for some peakiness of the highs when played loudly, I dare say the sibilance went away after 150+ hrs of burning, the trebles are now crystal clear and sharply focused and the only time I'll cringe is when I hear them play a demo of breaking glass (and that's a good thing for how natural the treble is)
Bass has gone tighter and more visceral and that smooth mids is to die for.
The last time I felt anything like this was back in the early eighties when I heard a pair of electro-static speakers for the very first time !
If you know what they mean by the Bass give the sound a fuller body on certain iems, I would say for the CKN70, the bass adds some at the low end and the highs add more from the higher end with the mids standing out all by itself.
I'm not sure if they've reached the final settled-in stage, will continue burning them in even though I'm perfectly satisfied with the SQ.
Guess you should be able to tell that they're my favourite pair of IEMs by now !
...everything I say henceforth would be bias ....at least until the CKN90 comes out !