HTC are actually going to continue to ship phones with locked bootloaders, and release an unlocking tool on the support website for them: presumably it's a warranty and support thing, and possibly a security one as well: it sounds pretty convoluted, but then, so is the current root exploit - su binary - engineering bootloader - S-OFF process to get custom firmware on there anyway. I'd prefer them to just have a button in the settings menu (like the Nexus One had for root), but the extra layers of "here be dragons" will probably stop people from doing it without realising the implications of trusting a firmware dev - if you could reflash phones straight-up, I suspect we'd see a bunch of custom Kesha ROMs loaded with trojans.

Actually, stage techs and live engineers use headphones for isolation, so they can hear what they're doing. They'll pull them off for listening to what the overall mix sounds like, and in a studio, where you can get reasonable quiet on demand, they'll listen on a set of frighteningly expensive ultra-flat powered monitors, since (you guessed it) in a well designed listening room, with good speakers and decent isolation, headphones don't even come close.