Thanks for the reply,.
I'm not interested in the XB-500., only the AKG K550, and whether anyone who wears glasses has used them and managed to get a good enough fit, or had serious difficulty with that. Obviously a good fit and seal is more important to the sound of a closed, compared to an open headphone. It might not matter for a headphone with as much bass as the XB-500 reportedly has, but that's beside the point.
Maybe I should start a thread with this specific question. I've read all the threads I can find about the AKG K550. I know their fit can be tricky; they can be adjusted, though maybe not for small heads. I'd like to hear from someone who's managed to wear the AKG K550 over glasses and get a good acoustic seal.