So I pretty much understand how headphone/speaker frequency response graphs should look like for a neutral sound, so what would be the ideal frequency response graph for IEM? They are stuck inside the ear so they must have a different response graph right?
let's say we use tyll's graphs, since he is pretty much headphone biased than iem, and set the HE500 as the benchmark for a neutral headphone, how much would a neutral IEMs defer?

















