Anji by Chicken Shack sounds just awesome in the UE 10s, but more modern music with more of a low-end fails a bit. Is this a weakness of headphones in general? Of IEMs?
It's hard to say with modern music if it's the headphones is simply the recording itself. There's always the argument for no replacement like displacement, but I don't know how well that holds up for headphones. I do find the bass in my new Grados to be very clean and able to hold up well with the low frequencies. A lot of which has to do with the actual housing. As soon as I put my hands over the open back area, the bass is completely diminished. It's incredible how much of a difference the enclosure makes. Not only is it the enclosure, it's also the ear cups. My point being, with so little room inside an IEM, maybe it's just a matter of physics that makes it difficult to reproduce the lows correctly.
What source are you using to drive your UE 10s and is the music format a lossy or lossless? Is it possible to find a sample CD that plays some test tones in the lower regions to see how well you can hear them as well as how the headphones can reproduce them? What I mean is, if you can't hear the 20-35 Hz range...maybe something is missing in the chain?
If you like the acoustics of Anji, check out a Pandora radio station of Nickle Creek. I know the quality won't be as good as a CD or even a higher quality MP3, but you'll get a good sense of some spacious-sounding and detailed guitars. I enjoy the music by Nickle Creek in general and I've been getting some good hits in Pandora for alternatives to the same genre.