I'm interested in what headfiers consider to be their "inflection point gear"
If you were to look at the amount of money/time you've put into headphones and related gear, there's probably some point at which you got a piece of gear where you saw your money/time put in increase suddenly. I'm not necessarily talking about the first headphones that made you realize what good sound was, but rather the first piece of gear that made you want to spend much more time and money on head fi.
I don't think I've been around enough to truly have anything I would consider inflection point gear, but if I had to choose one thing it would be my ER-4ps... If I hadn't lost them and gotten very, very sad, I think I would have started using headfi much more.