Just go for Ksc-75 for now and after some extensive audio poisoning u can upgrade to something better (and more expensive of course )

I have 2 friends who own a pair of ksc-75's each. I intended to get a pair as well but ended up with the Sennheiser PX100. I dare to say that both headphones produce very good SQ. Just that the PX100 is more comfortable in comparison with the ksc-75 which clips onto your ears. The px100 also fits more snugly on my head because of the headband whereas the ksc-75 hangs off the ears.

All in all the ksc-75 is still really cool in my opinion and for the price to pay its really worth it.

I use a pair of PX100 too. 2 of my mates have a pair of KSC-75 each and I am very certain that both pair of headphones leak quite a bit of sound. SQ is on par imho. Probably just a matter of physical appearance and preference of a clip on or headband.