I bought these earphones primarily for use with an IEM (In-Ear Monitor) system (on-stage musical jamming). They would work very well when doing sports or during commute or just casual listening. I came across these while looking through earphones sold on Amazon, and there are just so many of them (90% Chinese products)! These ones caught my attention, because one reviewer mentioned he used it for IEM. As usual, you save a bundle when buying from Taobao instead of Amazon.
I’m no audiophile, but i can tell that the earphones sounded really good, and i leave you to read the reviews by qualified audiophiles. KZ sells many other models as well and it’s really not easy to pick the right earphones. You should go for the more expensive ones i suppose, if you can afford it.
I took the advice of the Amazon reviewer and bought Comply Fit foam tips. They really do make a huge difference to the level of comfort when using the earphones (and maybe the sound too). The 600 series are compatible with the ZSR.
If you’re looking to improve your listening pleasure, i do recommend investing in this set of budget by high-performance earphones.