I'm still not sure who came up with "earphone" but I digress... For me, these are a great sounding, inexpensive set of IEMs. They are warm and musical with a punch in the mids. I have trouble in the 7kHz range and these compensate marvelously. of course, YMMV, but for the price, you really cannot go wrong.

I'm more of a lurker, but every once in a while, I will post something about a set of headphones or IEMs that are worth every penny of their cost. I own headphones and IEMs randing from $9.99 to $1999. While I love the high-end equipment, there is something about IEMs at the low end of the market that sound nearly as good as the high end.

Due to the price point, I buy nearly everything KZ makes. The KZ ZST are my go-to pair of inexpensive IEMs, and several co-workers bought a pair after listening to them on my Hiby R3, which I keep at my desk. Recently, I received a pair of KZ ZS7 "earphones". I don't know why I got them -- I only have two ears and over three dozen headphones and IEMs -- but they are my favorite IEMs I own.

The sound is warm and full. I have tinnitus and a constant buzz in the high 7K range, and I t prefer more musical, warmer tuning. The KZ ZS7s are clear and loud. For my tastes, these are nearly the perfect IEMs.

I compared these to the more expensive Fiio F9 Pros and while I like the aesthetics of the F9s more, the ZS7s I preferred the ZS7s in every other way. The same goes to comparing them to my set of Audeze iSine 10s. ( I should mention that I keep myHiby R3's volume at the 60 to 65 range most of the time, but when I plugged in the ZS7s I had to turn down the volume to 15, which surprised me.)

The cable that came with my set is surprisingly good quality. Somewhere a year or so ago I purchased a compatible "upgraded" cable that cost several times the price of KZ's highest priced IEMs. I usually can hear the difference, but this time the stock cable was just as good. Most of my KZs have a "bend" in the connector, but the wires that came with my ZS7s was straight. I'm unsure if KZ changed the design or whether these were non-standard cables.

For me, the ZS7s are my new favorite "every day" earbuds that are better than ones for which I paid hundreds of dollars. I want to be critical of these IEMs, but I really cannot find anything I do not like about them. I highly recommend these to anyone who likes warmer, musical sound profiles.

[I found out that this was purchased through Yinhoo The cable looks different than the KZ ZS7s from other sellers, which may or may not mean this company replaces the stock cable. https://www.amazon.com/dp/B07LF8J5K5/ref=cm_sw_em_r_mt_dp_U_tUb5CbEJV488C]

I am still new to the audiophile world and the terminology still confuses me. I may or may not develop an "ear", but for me, these IEMs are spectacular when it comes to cost-benefit ratio.

You can read technical reviews elsewhere, as well as a detailed explanation of the sound signature. Being a relative new comer, I will cover more mundane characteristics: aesthetics, build quality, comfort, and where I found them the most useful.

Aesthetics
I purchased the purple and blue version of the ZST. I'm drawn to bright, shiny things. Without the tips, the casual observer would be hard pressed to tell the are not custom IEMs. They particularly resemble UE CIEMs, though a tad less refined. The Cable is multicolored, though looks like muddled from a distance and feels rubbery.

Build quality
The finish is flawless, glossy and transparent. The beautifully laid out electronics are on display, which is a plus in my book. Each earpiece is stamped with a gold, stylized ZST. These earphones look like they should cost many times their asking price. The only part of the whole product that looks $20 is the cable which is finished to the same high standards but feels rubbery and the multicolor pattern looks muddy.

Comfort
For me, ZSTs are very comfortable despite not fitting well within my or ear canal. This is a problem I have with all IEMs due to my small ear canals. The provided tips are somewhat fluted and provide a comfortable fit and hold. Unfortunately, the units stick out from my head somewhat, so I cannot use them in bed. Despite this, I never felt uncomfortable or sore after wearing them for several hours.

Overall sound impressions
The ZST monitors are excellent for listening to vocal heavy songs. Singers, such as Elton John, Billy Joel, and Lionel Richie, all of whose voices dominate their songs, benefited from the ZST sound signature.

Songs where the instruments are just are important as the singer suffer, but only because the instruments are pushed back in favor of the vocals. To use an example, while listening to Queen, Brian May's guitar work is de-emphasized and Freddie Mercury's voice becomes even more prominent.

Pink Floyd has many songs where the vocals are almost "just another" instrument. Comfortably Numb, with it's soaring guitar solos , strong string harmonies, and percussion back beats are lost to the vocals. They still sound good, but I do not get chills down my spine during David Gilmour's solos

Then I changed the cable and everything changed. Sometime back I purchased an after market braided OCC cable, which I believe to be the same one used by the Magaosi X3 but with 2 pin connectors which I used to replace the rubbery thing provided with the ZST. And the music soared. Comfortably Numb once again sent chills down my spine.

Overall
Buy the ZST for $20 and invest in a $40 OCC cable. Yes, you are spending twice as much in the cable than the ZiEM, but for $60 you will end up with a pair of IEMs which, to my ears, sound better than, for example, $180 Etymotic ER3XRs. Definite thumbs up at the current price, but when paired with after marjet cables, these babies can compete with IEMs costing many times more.