You listen to one for a period of time and then go to put a different one on and all of the sudden it sounds weird and "off". For example, i listened to my ety's all this morning on the bus to college, they sounded off and weird for about the first 30 minutes i listened to them eventually they sounded normal. Then, i come home and put on my AD900's and start listening to music and same thing, they sound weird and off. Eventually they will sound normal again as i re-adjust to the sound difference.
It annoys me lol.