I'm curious about whether headphone manufacturers design different models of IEMs to be worn in specific ways to achieve the best sound. I've noticed that certain IEMs sound horrific when inserted deeply and only sound listenable when worn very shallowly, while others have the opposite problem. I just dug out my Nuforce NE700X today after my other IEMs all died on me, and I'm noticing that these sound terrible and muffled when I shove them in deeply with a biflange. I'm a bit of a basshead, yet these things still sound literally unlistenable to me when I wear them deep. They sound so bass-heavy and muffled that it's as if I'm listening to them with cotton balls over the drivers. But when I wear them with a shallow seal that isn't airtight, they sound great. So I'm assuming they were designed to be worn shallowly, but I don't see Nuforce specifying anything in the manual. Is this just a personal quirk with my ear canals or my taste in sound signature, or have other people found that the ideal fit varies a lot between different models of IEMs?