This is my first post here, though I've been reading for a long time. Go easy on me
I bought the E3c locally, then heard the reviews on the ER6i and ordered a pair from TTVJ. I've had both for about a week now, and I know a lot of you have been waiting for comparisons.
Some background- my collection has some rock, some jazz, and a whole lot of classical. For about 10 years now my only real pair of phones have been my trusty Grado SR60 and I love 'em. I know everyone says Grados are for rock, and yes they have that warm midbass and bright top end. But to me the top end on the SR60s is bright but never harsh, and I am very, very easily bothered by harsh highs, especially with solo violin.
The E3c is a weird 'phone. As someone else mentioned in the other thread, when you first stick 'em in your ears they sound pretty awful for a few minutes. They have a very pronounced upper midrange. People complain about the weak bass and rolled off top end, but actually I think it's just the overwhelming prominence of the upper midrange that dominates the balance. If you listen carefully, the bass is there- not great but not worse IMO than the ER6i or ER4P.
So first impressions not great, but here's the thing- if you listen to them for a while they are actually quite tuneful. I really can't describe it, they have a certain "bloom" that the Etys lack. It can create a sense of spaciousness and air, even if it is false. I find they are really great for chamber music. The boosted upper midrange brings out the woody overtones of string instruments, while the comparatively soft treble keeps violins from sounding too metallic. On other types of music they aren't so great. The balance is all wrong for rock IMO, and jazz is not much better. Before I got the ER6i, I listened to the E3c next to a friends' ER4P. The ER4P is much more neutral, but just a little too crisp up top for my tastes. Balance is more like my Grados, but somehow the Grados sound much more warm, sweet, and involving to my ears.
Next I got the ER6i. These are pretty decent. Balance is neutral like the ER4P, but softer at the top end. I agree with dkskywalker, these are not any more detailed than the E3c, probably less. Bass is pretty similar, but since it isn't hidden by that crazy midrange hump, it probably sounds like there is more bass. Rock sounds better on these, but chamber music sounds very lifeless and sterile compared to the E3c. You just get a sort of "tone" from string instruments, it feels like some of the overtones are missing.
In the end I think I will keep the ER6i because I'll still use the Grados at home and they are cheaper than what I paid for the E3c. But I dunno, I'll miss the Shures for some music. They are kinda love hate, but they kinda remind me of when I was young, listening to records of chamber music on some Sennheiser HD414s at a music library, didn't know anything about audio but just enjoyed the music. On the whole, I'm pretty disappointed with the choices at this price point, seems like you should be able to do better.
I think if you want decent bass at a decent price and are alergic to shill highs, get the ER6i. If you can try the E3c and like them, get those. And if you value a crisp top end and neutral balance, go for the ER4.
Peter