How did you manage to fix this please Tiaeki?
I have the same issue with my new X11i. Attached to an HTC phone, I experience external noise which is definately an anomaly and shouldnt be there. I have attached the X11i to my Alienware laptop and the result is the same = noise. It is heard all the time a track is played, mostly comes up in silent passages. I have attached my AKGs to the HTC phone and no such issues. Also as you have mentioned, headphones mic is recording everything and creates garbage sounds in the headphones - also in case when there is no playback.
Klipsch team - what do you think?