Here's a mod:
I had a problem when I bought the XBA 30 in Bangkok's airport, as I felt they are not completely ballanced
between the channels. As I result, I removed the foam inside the nozzle, and replaced it with foam that
exists inside the special "noise cancelling" tips that are provided with the XBA. Since one does not
use all sizes of these tips (I doubt that they make any difference anyhow), you can cut carefully these
foams. From their looks, they might be exactly the same as the original matterial. As I do not hear
completely equally in both ears, I added some more of these stuff in the right ear. Also, this helps to
remove the strong peek around 4khz.
What I am curious is why I heard quite a large different between the two channels (I tested them in
the same ear, as I do have some difference): the sub-bass was much stronger on the left channel. I have
a particular sensitive musical hearing, and am very sensitive to this.
Overall, I find these earphones, albeit not perfect, the best that I have so far encountered, including
the UE TF 10, which I have (actually UE TF 15vm, which is the chinese version, but its the same).