To date I haven't heard a purer representation of "audiophile quality" sound than through my Etymonics which I bought a decade ago.
The treble is inoffensive, yet it sparkles and brings out every single detail. The full-size cans I have listened to elevate the higher frequencies to artificial levels, and cause painful, ear piercing sibilance. This includes the Beyer DT series, Grado sr80 and sr325s, and to a lesser extent the D2000s.
Despite the sparkling treble, the mids are completely natural and unaffected. They are not recessed at all, and to me they are some of the most tonally accurate headphones I've heard. You close your eyes and you can imagine the vocalist singing in your head. Many of the headphones with treble emphasis, like the ones above and the D600, will bleed into the upper mids causing weird vocals that don't sound natural at all. Even worse is the sibilance of the "S" sounds. Dark headphones like the HD650s and Sony XB series will sound veiled and hollow almost.
People always say the bass of the Etys are lacking, but they're not. It's just that they're completely level with every other frequencies. Bass heads like myself usually want a bit more power in the low end, but I've learned the etys aren't lacking at all. I was just listening to some Digital Mystikz for example and they hit even the lowest notes with authority. They reach just as deep if not deeper than the infamous D2000s, and even better is that the bass is accurate. You can hear every difference between the bass notes.
The presentation is as perfect as a pair of IEMs can get. Completely completely neutral. Pinpoint accuracy. Perfect imaging. Perfect separation. Transparent. They just don't have a wide soundstage which is understandable since they're IEMs. But they actually separate instruments better than most headphones I've tried, especially portable ones like the AT ESW9.
Through the dozens of headphones I've tried, and thousands of dollars I've cycled through I've never found a pair that compares. The closest is maybe the a900x, but the bass doesn't extend as deep and the highs aren't as detailed. Bigger soundstage though.
So any suggestions?