KZ is a Chinese IEM company that specializes in making budget grade earphones, and is well known for their high-value offerings. While they have made pretty big waves in the Chi-Fi crowd, they remain relatively unknown to the broader Hi-Fi community. That’s a real shame considering they have some very compelling products, including the ZST Colorful that I am reviewing today.

You can find the KZ ZST on at Penon Audio, here, for $20.

Disclaimer: This review is based upon a sample unit provided to me by a manufacturer or distributor in exchange for my honest opinion and un-edited words. I do not profit in any way from the writing of the review. I would like to thank Penon Audio and KZ for sending me this review unit.

Preference and Bias: Before reading a review, it is worth mentioning that there is no way for a reviewer to objectively pass judgment on the enjoy-ability of a product: such a thing is inherently subjective. Therefore, I find it necessary for you to read and understand what I take a natural liking to and how that might affect my rating of a product.

My ideal sound signature would be an extended sub-bass with a leveled, but textured, mid-bass. The mids should be slightly less pronounced than the treble, but still ahead of the bass. I prefer a more bright upper range.

Source: The ZST was powered like so:

Nexus 6P -> earphones

or

Hidizs AP100 3.5mm out -> FiiO A5 3.5mm out -> earphones

or

HiFiMAN MegaMini -> earphones

or

PC optical out -> HiFiMe SPDIF 9018 Sabre DAC 3.5mm out -> earphones

All music was served as MP3 @320Kbps or as FLAC.

The ZST scales decently well with higher-end sources. It didn’t take too much amping to achieve high volumes.

Sound Signature

Initial Impressions:

The ZST has a warm-leaning sound signature, but doesn’t swing too far away from a balanced presentation. Bass presence is slightly boosted, as are vocals. Treble is present, but well balanced with the mids.

Treble: Songs used: In One Ear, Midnight City, Outlands

The high-hats of In One Ear were quite clear, and presented well. I expect nothing less from a hybrid IEM from KZ. Upper-treble decay is fast and precise, with no noticeable truncation.

The electronic synths in Midnight City were placed in the middle-back of the song, but never became inaudible. I’m impressed given how well the tonality of the synth was preserved despite its background positioning.

Outlands sounded reasonably open, with decent spacing and air. However, I found that violins were only of average clarity, something I still find to be quite a feat to my spoiled ears for a paltry $20. While I could certainly hear the foreground violins quite well, the background ones did not fair as well. They tended to fade in and out of audibility.

Mids: Songs used: Flagpole Sitta, Jacked Up, I Am The Highway, Dreams

The mids of Flagpole Sitta were well defined and separated, but lacked some of the finer details present in some (much more expensive) IEMs. Guitar tonality was decent. Electric guitars lacked their usual intense power, but were still clear in the mix.

Jacked Up’s pianos had a softer edge to them, indicating a slower attack and decay in the mids. The guitar feedback sounded decently lifelike, but I found that separation was a little worse in this song. The ZST does tend to show its limits when presented with lots of mid-bound instruments, and more so when some of them live in the background.

Male and female vocals are presented equally well and naturally weighted. I really enjoy how they interact with my music, and really enjoy their presence overall.

Bass: Songs used: Moth, Gold Dust, In For The Kill (Skream Remix), Leave Me

Bass is present, with a slight boost. This really helps it express itself in rock and acoustic songs, such as Moth. The bass guitar, while more subtle in presentation, was still audible and dynamic.

The bass in Gold Dust had good impact and tonality to it. While it should certainly satisfy the average listener, I found my inner-basshead looking for more rumble. However, a quick boost to the 30Hz-100Hz range sorted that problem out quite nicely.

Sub-bass expression and dynamacism was quite good, with the ZST pushing pretty far down into lower frequencies. This made In For The Kill quite enjoyable, despite the ZST not being tuned for bassheads like myself.

Packaging / Unboxing

The ZST is packaged sparsely, but that’s not really a problem given the very low price these things sell for.