The KZ ZAX is KZ's newest hybrid iem. With 8 drivers per side (7 balanced armature, 1 dynamic), the driver war for chifi iems continues, and we are all the benefactors. The ZAX are the most premium and best sounding KZ iem I've tried to date, and I think these new wave of 16 driver chifi iems are really knocking the value prospect out of the park. If you were looking for the short and skinny of it all, I absolutely loved these iems, and I think that for the price, you can't go wrong with these. For the details, read on.First thing to talk about, the build quality is impressive for a sub 100 iem. There is a beautiful matte black finish on my unit that blends nicely into the universal plastic mold. The pin system isn't my favorite, and causes some discomfort, but overall, the iems are quite comfortable and I have no issues with fitment issues. For most ears, I suspect this will be the same but I've had a friend that didn't quite like the fit. The cable and accessories are the standard affair for KZ at this point. Star tips, decent silver colored cable, and a black box with a "plaque". Not the best in terms of accessories.Though the cable is decent, I ended up buying a nice Kbear 8 core cable that I found more supple, a lot higher quality, aesthetically more pleasing, and just an overall better fit. I'm not one to really talk about how cables differ in sound and quite frankly, I did not really hear a difference in sound but I did find that these fit over my ears a lot better than the stock cable, and the whole package was far more premium and enjoyable to use with it due to the thickness and softness of the cable. It also has a nicer plug, and connectors, and comes with a little carrying pouch which is just a nice touch. Overall, I was pleasantly surprised with how nice it was considering the cost of much higher end cables from other audio companies. While it's not necessary, I would definitely consider looking into aftermarket cables if the stock cable just doesn't do it for you.In terms of isolation, I find it to be about average. Nothing crazy, but considering the vents on the back, I thought they would leak and isolate a lot less, though that was not the case. For your everyday usage, I think most people won't have any issues with isolation. One thing I cannot speak on in terms of ergonomics, build quality, or sound isolation is the durability of the whole package. While I found the fit and finish astoundingly good for the price, I have no idea if the faceplate will scratch in your pocket, or if it would survive a drop. I've had these for about two weeks and while they still look great, I wonder how the matte faceplate will hold up to keys in pockets or whatnot. My recommendation would be to keep them in a case if at all possible.We'll move onto the sound portion of the review. This is where the ZAX really shines, and why spending the little extra really pays off big over cheaper iems. For an iem of this price, there is definitely a level of elevated performance that chifi iems of this price point 2 or 3 years ago couldn't compete with. The overall sound signature I found to be slightly V-shaped (though not overly aggressive). The soundstage on these iems is pretty large and definitely above average as a result, and instrument placement is good as well. If you're a mid head, you might want to see if you can try these first to see if the sound signature bothers you, but I find the iems to be remarkable value and it would be a shame to not look into them based off of the "sound signature".When talking about highs, I usually associate KZ's older lineups with great technical ability for the price but shrill/strident highs that many people just couldn't handle. I think KZ over the years has done a remarkable job taming the highs while still giving it some sparkle and shine, and allowing good technical details to shine through. The ZAX is no exception. The highs are clean, crisp, and extend well. High hats, high octaves, and a lot of energy up top allow this iem to sound pretty clean, exciting, and technically sound. However, I find the sound signature to lend itself to being a little bit more laid back. This will likely benefit the average consumer more and makes the iem an easy recommendation due to it being an easy and enjoyable listen.The mids, while "recessed" when taken into context the sound signature, still sound full bodied, accurate, and pleasing. I don't think these iems display an aggressive V-shaped tuning, so I don't find the mids to be overly recessed. However, I don't believe them to be in your face and personal like some iems can be. For that reason, if you know for a fact that you enjoy very personal sounding soundstages with vocals being upfront, up close, and personal, these iems might not fit the bill. Again though, I don't think these iems commit any cardinal sins by sinking the midrange so far recessed that they sound strange. There is plenty enough midrange presence.The lows for me show why I absolutely love hybrid low ends. With these iems, you get the speed and cleanness of the balanced armature drivers, and the dynamic and hefty low end. Bass bleed was minimal, while being dynamic, punchy and overall pretty cohesive. Though hybrids sometimes suffer with cohesiveness due to the two different driver types, these iems are tuned nicely and that issue is minimal. The bass extension is good, and you won't be missing anything in terms of low end oomph. If you're looking for bass cannons, these may not be for you. But there is definitely good weight and energy in the low end.Overall, the ZAX really shows how far chi fi has come along the years. Though there is a lot to be desired in terms of accessories, the true value of the In-ear monitors come in the form of astounding performance per dollar, and superior build quality and aesthetics (subjectively for looks). If you're curious how far chifi has come, want to see what KZ's newest iem has to offer, or you're just looking for the best bang for your buck in audio around, the KZ ZAX is the iem for you. Don't hesitate to buy this if you have the means and you're looking for a new iem. They're that good for me to recommend. Even though driver count doesn't always equate to better performance, the ZAX definitely showed a level of sophistication and technical prowess that I've yet to see in this price bracket. For those reasons, the ZAX is an easy recommendation for me.