I know this is a KSC-75 fan club but...
I just got my 3rd Koss a few days back, the KSC-55. I have two KSC-10's i bought a long time ago.
I'm definately liking it more than the KSC-10. As some say it's more bassy than the KSC-75, and true, it definately sounds pretty strong on the bass. Has better clarity than the KSC-10 also of course. I suppose as people describe, the KSC-75 is much less bassy or much brighter. Don't know what else to describe, I don't really know how to describe headphone sounds. Ah and, the bass this thing outputs really made the engine sounds in Live For Speed so awesome and immersive.
I've not burned in yet btw.

Haha I'm used to wearing behind the head's so no issues for me. New pairs always feel a bit tight, after that they are fine. I can sleep with them too.