If you can read Japanese, this site has some XBA-C10 customer's reviews.
1) Sony XBA-C10 has bright, high resolution, clarity and suitable for strings (guitar) and female's vocal/singer.
2) Bass is there, enough for some people, but not for basshead..
3) The main attraction is the COST.
4) Fitting is good and very lightweight.
From the evaluation table at top left:
Generally, C10 got better than average evaluation in, design, treble, noise isolation, sound leakage, portability and cost performance categories.
Design and bass quality, are a little bit lower than average.