I think I want a CIEM. Even though the HD800 is the most comfortable full-size headphone I've ever owned, the size and weight are starting to wear on me.

I also think the shape of my ear is different enough on each side that it is having an effect on how I perceive sound with large headphones. Things on the left side sound like they're closer to my ear, while the right sounds farther away and more forward. I notice this with full-sized headphones, not just the HD800. When I use IEMs, like my Pistons, the effect is greatly reduced. In fact, there have been many times where I think I have preferred the presentation of sound from my IEMs.

For sound, I'm an unabashed detail whore. I want to hear absolutely every miniscule detail in my music. I generally like the way the stock HD800s sound, but I wouldn't mind less treble energy, especially in that region that seems to sometimes cause female vocals to have an almost ringing effect. More "coherence" (is that the right word?) would also be preferable.

Bass is also important. Having at least as much quantity, detail, and extension down low as the HD800 would be ideal. I listen to a wide variety of music, so a CIEM that's peaky or has a limited genre performance envelope is not something I would be interested in. Soundstage isn't that vital to me.

Right now the two top contenders are the Ultimate Ear Reference Monitors and the Noble K10. I'm attracted to the UERM because of price and neutrality, but the K10 has so much universal acclaim as the "best" CIEM currently available that I can't ignore it. In fact, multiple people I've talked to about this online have told me directly that they preferred the K10 to the HD800.

My amp is a Schiit Mjolnir, so I would need a balanced cable, though I am open to selling the amp if something else would be a better choice for a CIEM. I really like it, though, and I paid less than $500 for it. I just don't know where to actually get a cable.