Ladies and gentlemen may I have your attention please.....
TA-DA! My ZS6 just arrived in my mail today and I have never been so excited for a package ever before!!!
Soundwise they are a HUGE step up from every other KZ model I've tried, especially regarding clarity, detail, and imaging.
First of all let's get rid of the elephant in the room and talk about that overdone treble. There's no denying that the treble is kind of overkill, but I did what everyone would do and changed the stock starline tips to a different set of tips which drastically reduced the piercing treble. Seriously, it was literally like from sitting on a bunch of spikes to sitting on a nice comfy pillow. The starline tips seem to really emphasize the upper highs, which is actually a con in this case. I actually find that quite ironic because the starline tips works wonders on every other KZ IEM except for the ZSE and the ZS5/ZS6, which are the only KZ IEMs that include them. Later on I'll probably do a foam mod by inserting foam into the BA nozzles to tame the highs even more.
Okay with that out of the way, I cannot believe how detailed they sound. They definitely brought out many details that were usually unnoticed with all my other IEMs. I used to think that my ED9 and ATE-S were quite revealing (in the highs and in the mids respectively), but the ZS6 was basically like "no, I'll give you EVEN MORE details!!!!"
And I don't know how to explain it, but music overall just felt more "alive" and "realistic" with the ZS6. It felt like I was completely immersed into the music. Definitely a good thing whenever you want the music to control you; it literally begs you for your attention, so be careful with multi-tasking or else you'll be more focused on the music than the thing you're trying to do (e.g. homework).
Sound
signature wise—well I honestly never paid much attention—but I could tell and already knew that they have a large emphasis on mids/high-mids, which made stuff sound more realistic and "concrete". I honestly didn't pay much attention to the bass either, probably because it was so well-meshed into the music, but I can say that it is neither bass-light or bass-heavy; it has the perfect amount of bass that you could wish for, and its sub-bass to mid-bass ratio pretty balanced.
So having said all that, the only thing I really wished was for the treble to be less piercing and to be a bit more relaxed yet detailed, kind of like the treble on the ED9. Too bad I missed out on the ZS5v1, the treble on there from what I heard seems to be much more "relaxed" but detailed sounding.