KZ ZST and ED12 first impressions, $25 IEM shootout

$25 IEM shootout pre-amble

One of the coolest phenomenons in audio right now is the big improvements moving forward in the budget sector. $100 headphones can and do compete with $400 headphones, and $25 headphones sometimes compete with $200 headphones. It’s a great time to be an audiophile, even if your budget isn’t as large as you’d like it to be.

In this $25 IEM shootout series I’ll post a new set of impressions every Wednesday until I’ve done them all. Then I’ll select my top 3 from the list. After I’ve selected my top 3, I’ll do a post ranking the remaining units and giving them our trademark visual ratings. Finally, a post will compare the top 3 IEMs under $25 that I have in my possession. If any manufacturers want to send additional under $25 units that they think might rank before I’ve done my ranking posts, I’ll add them in.

Here are our contestants:

*I’ve included earbuds. My blog, my rules. I know there’s a difference.

Unboxing / Functionality

When the ZST came out, it was one of the cheapest hybrid (BA and dynamic driver) IEMs in existence and KZ was pretty new to the scene. Packaging was a pile of sad.


Just a simple black box, with a blown plastic insert showing the headphones in a generic entry hole in the tray. The card saying ZST is exactly the same as the one saying ED12 on the ED12. The packaging doesn’t come with retail hooks, or anything to make you think this is anything other than a budget offering, which is actually fine because these are a budget offering. You can get them for $9.99 without a microphone from Linsoul now.

The cable included with the IEMs is nothing special, but it is detachable and therefore replaceable. The cable looks a lot like what came originally with the Fidue A65, but this cable has a kind of tacky feel to the plastic (fingers kind of stick a bit). The strain relief on the cable is good, even at the y-split. The KZ brand uses bespoke 0.75mm 2-pin connectors, whilst the industry standard is 0.78mm. I’m here to tell you that you can force 0.78mm pins into this without difficulty, without damaging the 0.78mm pins, and without affecting the sound. It isn’t even a ‘Like A Virgin’ moment (NSFW). The first KZ headphone I picked up was for the explicit purpose of putting a slightly large pair of pins into something I didn’t have to worry about breaking (Lear BTC-01: a sound surprise in wireless).

The pinholes can take more pin size than the label on the box would indicate, so don’t worry about trying other cables out, you can still use KZ’s cables afterwards. There is another peculiarity in design that KZ has done, their eartips. I don’t know why they think this looks like a star. It has too many points. If they had done a six-point star, I’d say this looks like a star, but with a 10 point star, that’s a cat’s butthole. The tips, outside of looking funny are mediocre tips. There are better fitting tips out there with better sound profiles. I’d advise that they would be better off ditching the butt tips.

The microphone on the microphone cable has average quality. It is at a good location on the cable. It would have been nice to have more than 1 button, but I understand and support the likely savings from not having volume controls on the built-in remote.

The shell of both the ZST and the ED12 are plastic with a noticeable lip where the faceplate is glued to the body. The shape of the shells isn’t pseudo-custom, but it is trying to look like it is, which makes these look more premium than they are. These don’t have the ergonomics of a pseudo-custom fit, but then they don’t have the price either. Pseudo-custom shells tend to come in at a minimum of around $100, so this form factor works pretty good under $20. The plastic doesn’t look terribly durable, but I haven’t tried to smash ’em. I’d like if KZ, or most of these budget makers included a case, but if you want these to keep ticking and protect them, I suggest you get one. On Gearbest I found some KZ official cases for about $1—it would be easier for everyone if they just included them.

Sound impressions (ZST)

Sound impressings were done using the HiBy R3, which is my favourite budget player right now. The R3 has a little bit of fun to the signature, but not too much.

  • Bass on Natalie Merchant – Carnival is groovy and big but a bit loose, with a midbass focus. Some of the texture and depth are missing. The midbass is forward in the mix. Natalie’s voice is recreated well. Good for a tenner, but definitely missing some texture in her voice. Stage depth is shallow. The cymbals are missing a bit of the body of their shimmer, with shortened attack and decay. This quick attack and decay gives a bit of more metallic sheen to the sound. Hand drums sound really good on the ZST.
  • Female vocals sound good on these. Kate Bush – Cloudbusting has lovely sweetness but misses a touch of her . As with Carnival the elevation of the midbass is clear. The elevation here doesn’t hurt the vocals, so it will be pretty satisfying for a good proportion of the folks shopping in the budget sector who are used to a bit of elevated midbass and like it. It’s a good tuning. Drums sound good on this track too, with some nice impact—this isn’t uncommon on IEMs with elevated midbass.
  • The instrument separation on The Beatles – Help! is limited by the depth of the stage, with the sound ending up in a bit of a wall of sound. The instruments don’t muddle together much, but the spatial limitation makes picking out individual elements more difficult than some other IEMs. Stage width is actually pretty decent. Height is pretty average.
  • Drums slam huge on Outkast – Ms. Jackson. The background synth is a bit buried in the mix, which removes a touch of drama from the track. Still sounds engaging and pretty clear, just not the kind of black background that you get used to when listening to higher end models. The sound is pretty satisfying with hip-hop.

Sound Impressions (ED12)

  • The ED12 is basically the ZST with a darker sound. I wouldn’t be surprised if they share their dynamic driver, which would mean that BA treble isn’t really there.
  • On Ms. Jackson the bass is comparatively over-egged because the treble isn’t there to lend a bit more clarity to the midrange. These still sound all right. There aren’t actually many terrible sounding headphones out there, but these are missing substantial bits of the music. This track has lots of percussion detail and it’s largely just gone.
  • Cloudbusting is also missing some breadth to the tonality, the emphasis in the bass isn’t balanced out by treble. There is just less detail and definition across the whole frequency spectrum. The sound is somewhat muddy compared to the ZST. It’s like the sound has been busted by an actual cloud hanging omnipresently in front of the music.
  • Depth on Carnival may actually be a bit deeper than the ZST, but the frequency response is less balanced which means the characterisation of the music is less accurate.
  • The ZST are better than the ED12.


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