Is the interaction of quality headphones/iems and the human body kind of like drugs, in that our body quickly develops a tolerance to it, and it keeps taking more and more to give us that "high?" Anyone else had the experience that: you used to feel so great listening to your low-end equipment, but after you had a chance to try some better stuff for a significant length of time, your lower-end stuff not only no longer made you feel good like it used to, but it almost seemed unbearable to listen to, would give you a headache, etc? It makes one wonder. What if one was stuck on an island or something and they had to listen to their lower-end stuff forever, and never were exposed to higher end equipment? Perhaps the lower end equipment would keep giving them that great feeling forever, as long as they weren't exposed to more quality equipment? I used to feel a natural high when I listened to my Sony Walkman & buds in the mid 90s. But then something better came along that I started to use, and then the Walkman no longer got me high. Same thing happened just recently. Had the Creative eps630 iems, and they made me feel great when I listened to music. After my friend let me borrow his UM1's they got me high, and the eps630 no longer did anything for me. I had to buy some UM1s. Then I got turned onto some Superfi.5Pros, and now they will give me that natural high, but the UM1s don't do much for me. None of the former iems above will do much for me now, when I try to revert back to them. Human physiology is interesting. Anyone else had this strange experience of owning equipment that you used to really really enjoy listening to, but now its almost unbearable to listen to and actually gives you a headache, etc?