Just bought my can yesterday evening. Below is my experience to share after listening for 3 hours. I am not an audiophile expert, try to describe as best I can.
My K550 is powered by Rocoo P DAP. when listening at home(pretty quiet, except the floor stand fan noise), volume set to 15 is sufficient. this can do need to drive at slightly higher volume to bring out all the sound. When I test out the can at the retail store in a shopping mail, need to bring volume to 18-20. the noise isolation is pretty good, especially when playing song, can hardly hear the noise from the shopping mall. I think this will works well for me on a 20hr flight. Bass is tight, not your "bass head". Soundstage is wide, clear and clean vocal, good dynamic, can hear all the instrument playing clearly. I can start hearing some instrument clearly than before. As for fitting, not much a problem for me, maybe I have a "big melon", clamp position set to 3-4 give a nice and comfortable fit during the 3 hours testing at home. Did notice some cracking sound at higher frequency instrument, probably need to "burn-in" to smooth out.