To celebrate the 10th Anniversary of the brand, KZ launched the KZ ESX. It is a budget earphone equipped with a 5-micron self-developed liquid crystal diaphragm 12mm new frame dynamic driver.
The ESX’s shells are made of a transparent material that gives you a clear view of the IEM’s internals. KZ has implemented metal alloy faceplates with a cracked design. The faceplates are grey in color with light blue lines. 
The shells are comfortable and fit without any problems. Although they are slightly on the bulky side so if you have small ears you should think twice. I can happily wear them for long listening sessions on my average size ears. The passive noise isolation is not bad either, with music playing quietly I can barely hear anything else even in noisy environments.
You get the standard KZ flat SPC cable. The components are all made of opaque plastic but the handling is decent. However, it tends to get tangled pretty easily.
Specs
- Driver type: 12mm Liquid Crystal Diaphragm Dynamic Driver
- Frequency range: 20-40Khz
- Impedance: 22 ohms
- Sensitivity: 112db
- Pin Type: 0.75mm
- Cable Length: 120cm
Price: $18-$20
I would like to thank Linsoul for providing me with the review sample of KZ ESX (no affiliate links). Amazon, Aliexpress.
Sound
Lows on the KZ ESX are on the elevated side of neutral with good texture and rumble. You can feel the impact with each note of the rounded, weighted bass. Separation in lows is there and that’s welcome in this price range. Plus the tonality and quantity are very good for the price, better than I expected. The note definition is also good to figure bass lines out especially if they go down deep. Kicks also have a good slam but are not the fastest which is very expected. For a budget IEM, the quality of the dynamic driver is pretty good.
The mids have a good amount of resolution and clarity. They sound natural, the timbre presentation is good and the tonality of the instruments is on point. ESX crafts a warm and full-bodied midrange with the backing of the mid and upper-bass. Vocals sound natural, upfront, and well-defined in the songs. No harshness in high-pitch vocals either and this is very important in any headphones and can be a real deal-breaker in some situations. Acoustic guitar, piano, and brass instruments all sound lively.
The treble performance of KZ ESX has good clarity, is sparkling and airy enough, with a very good sense of space. The treble tone is slightly warm and smooth. You won’t hear any sibilance either. The details are clearly exposed and easy to hear. Vocals and cymbals never get sibilant or harsh. The balance between safe and too bright is well done. Treble area continues at the same level of lows and mids, very well controlled. Sound rich, defined, and well extended for an IEM at this price range. This gives you a good level of clarity and detail retrieval.
KZ ESX does a good job when it comes to separation both in layers and instruments. The soundstage is also much better than I expected. Is wide and deep enough to enjoy your acoustic and instrumental tracks. KZ ESX scales and extends very well with power and a good source, even though it’s easy to drive, you surely will have more fun if you use a USB DAC-AMP at least.
Sum-Up
There is nothing wrong with KZ’s 10th Anniversary ESX. It’s one of the good alternatives for the $20 segment, especially if you want a detachable cable for your budget purchase. Although, there are some Zero’s on the market that you might want to check if you like a less bassy and more natural-sounding alternative.