i feel like in between.
@Akroma your experience is totally normal, your x5 is working fine, and you should happily enjoy it. I would make a stretch if i were you, and get better headphones, ultrasone dj one, or sennheiser hd5XX or akg k550, or sennheiser urbanite xl and you might enjoy music even more. One advice would be to not get ath m50, i considered it under hd 419.
Listening at loud volumes is bad for your ears, but i can totally understand that thing, as i end up listening loud some times because i listen while walking and the city noise is too high for music to be heared how it should, It is not good for your hearing, but as long as you don't end up at the end of the day with ringing in the ear, everything is fine. if at evening, or when you go to sleep you hear tinnitus, you are listening too loud.
another advice that would be usefull would be using EQ to make it seem louder without it being louder. For example, i want louder cymbals, but i am fine with mids and bass at lower volumes, because i am used to live music, un-recorded, but real live music, which has some louder than ever other instrument cymbals. so i use eq on x5 to add to treble, +4db, and i can listen at much lower volumes, because it is easyer for me to hear very fine details ^_^
at the end of the day i end up protecting my hearing, and enjoying more!