I got the PX 100's for $40 used. Man it feels so great to finally have some legit headphones, one thing that immediately caught my attention is that listening to music at medium-high volume doesn't hurt my ears.
I also noticed in some music that I used to listen to regulary, is that I hear new "sound", perhaps its just because sound is really clear.
So awesome. What would be a major upgrade to the PX 100? I really want to get some high end headphones for christmas.