I'm not really a basshead as well, I just like that cinema-type rumbling, experimental music and sometimes I crave guilty pleasures in the form of simple pop/hip hop beats, but X1, while very competent in the bass department, didn't rumble enough in a few cases.
Anyway, my amp is my Essence STX's amp (32-600 ohm, I heard it's a bit too much and muddles the sound, so I'm going to try fixing that in the future). Vocals are definitely better on the X1, middle is more detailed, highs as well (but, as I outlined above, S680 isn't really that much worse in the treble department, it holds its ground). While the signatures themselves are close to each other (S680 is definitely darker, but there's a lot of fun to be had with both), X1 has much less bass (while having a lot anyway, they are definitely not analytical in any way). But it's similarly controlled and does not spill into mids with both cans.
- edit -
Oh, and the stage is much better on the X1, but I assume that's obvious. :)
Edited by aidenn - 7/30/14 at 12:19pm