I have been using these earphones for a few months now, and I can honestly say that I am very impressed. I really did not expect a pair of $12 earbuds to sound that much better than the $6 earbuds that I've been using before.
Objective sound quality
My stationary headphones are Audio-Technica ATH-M50x, which are considered one of the best (some swear that they are) cans $200 can buy, and obviously KZ ATE don't sound quite as good, but it is not a fair comparison. I really love the sound, and they sound far superior to any other pair of sub-$25 earphones you get in retail.
They are loud, and so far are free of distortion. They have soft and slightly warm mids that sound quite natural. The high's have a good range, and don't get in your face as long as you are reasonable with equalizer. They do take well to heavy equalization, which is a good indicator.
I expected bass to be a bit more distinct; but with the bass booster EQ they get better. Important to note, that mids do not distort with a strong bass/sub eq bump.
These headphones are very analytical, and have an adequate sound reproduction for electronic / instrumental music, less busy music with simple vocals, and classical tunes. Because of the closed-type earbud (that inserts into the ear canal, vs. covering it entirely), the sound appears concentrated, rather than giving an impression of “being there”, which is understandable for the price.
These earbuds have a fantastic for the price build quality. The cable doesn't tangle much, and it is completely free of microphonics (the annoying rustling sound when the cables touch each other or the surface). The plastic is thick, and the assembly is very much acceptable: there are no visible weak spots or rough edges.
I got an impression that they would last – but the time will show.
The fit is a bit unusual. If you never had earphones shaped the same way, you will have some getting used to do. You are supposed to wrap them behind the ear, and the silicone shaping brackets help the cords take the correct shape (I use them without the silicone tips though, because it was getting too uncomfortable as I wear glasses). But since the cable weight is evenly distributed between and supported by your ears, you don't really feel them. Even after listening this amazing Drum&Bass set 2 hours, my ears did not feel tired as they did with Awei ES800m.
There are 3 sets of tips included, 1 pair of foam ones, and 2 rubber. In my opinion, the foam tips are much better than rubber tips, they just feel softer and more comfortable.
Bottom line: Great build quality, solid isolation, and distortion-free analytical sound that is suitable for electronic genres. While the sound is crisp and clear, it is concentrated – thus not very delicate, and it can be fatiguing. It might feel like I'm overselling them a bit, but I promise, they are worth every penny, and more.
I still consider them a good budget buy – I regret nothing.