ok
if it is cable problem, i can solve that by recabling.
however, there's some time, user twist their cable at the earphone there. and DAMAGED the voice coil. (voice coil sits right under the wire, near to the earphone there. and protected by a very thin layer of soft glue)
that one i can't do anythings. as i need more than 2 hours surgery to settle that. i don't dare to charge RM100++ for that. u better go buy new one if this is the case.
u have to hand ur ksc75 to serdang.
i will detach the cable and test ur ksc75 with multimeter. if it is ok, means voice coil is ok. else. it's died.

ps: coolerthings also has one unit, sometime twist cable got sound (the cable push the vioce coil to touch and connected. when u not twist, the voice coil is disconnected). we all though it's cable problem. but after recable, no sound. and still have to twist the new cable to get sound.