[/IMG]
First impression: Although I am not a big fan of any sort of Chinese brand like Xiaomi, I cannot deny the merit of these inexpensive IEMs in terms of sound quality. As you can see, I am insanely comparing it with my ASG 2.5 which cost somewhat 20X of the Xiaomi. IMHO, I'd say the 5th gen can roughly achieve 70% of what my ASG 2.5 does. That's how fast and crazily our technologies advance nowadays.
Build & fitting: comparing side by side, I find the canals of the 5th are slightly thicker than it's predecessor, and the same applies to the housing as well. Personally, I prefer the clothed cable from the 4th. Nonetheless, both 4th & 5th are well built. In terms of fitting, I find the 5th gen doesn't fit my ears as good as the 4th which might be due to the subtle angle of the housing in addition to it's angled canals. Consequently I need to use different tips on the 5th in order to get a proper fit.
Sound quality: as mentioned earlier, the 5th sounds amazingly right out of the box, to the point I was comparing it with much higer tier cans. People have widely mentioned the enhanced calrity on the 5th over the 4th, to my ears; however, that's not 100% the case. The 4th sounds fuller and warmer to me while the 5th seems to be a bit thin and quiet. That said, the 5th does not lack any bass, in fact it is more controlled I think. By far, I haven't encounter any harshness nor distortion on the treble spectrum like other members mentioned, even when I drove the 5th with high gain on DX100 (at volume 182). All in all, the 5th is very musical with faster pace than the 4th. Still, I would say the 5th cannot completely replace the 4th due to it's slightly cold sounding.
Wish everyone enjoy their music