I own the T20i and I will try to share my experience. I will talk about sound in a very basic way, also you can check web pages like head-fi for that, they got all what you need.
what bothers me about T20i:
- The wire is though and rugged, but the material it's made of( high friction rubber), so it like to stick and grab to things.
- the cable is not straight and its a bit hard to get it straight, because of the thick wire. So you get a rugged, strong wire but lose flexibilty.
- the wire is not dettachable since there is many do have this feature in the price rang.
- they are comfortable after a while of adjusting and trying different ways to bind the upper part of the wire. Maybe because of my ear shape YMMV.
Now after all that negative points, I will write about what I like.
- sound filters that actually work proven by brooko from head-fi
- lots of accessories: Silicon tips, few foam tips, carrying pouch, sound filters
- sound signature in general wich is warm and energetic. With the right amount of bass, clear mids, and detailed clean & clear highs. However, the highs was a bit harsh for me, as I usually like to hear my music loud. But I've changed my bad habit and have no problems, lowering the volume one time on my note5 will remove the harshness. For more details on sound and more professional analysing look at head-fi !