Wearing Style
In ear (IEM)
1 x 10mm Dynamic, 1 x balanced armature
24 Ohms
112dB SPL
7g per earpiece (Without tips)
Cable connector
KZ C-pin (0.75mm 2-pin)

Today I’m looking at another budget-fi / chi-fi earphone. This time the KZ ZSN Pro which from Ali Express costs as little as £10. £10??? How on earth are these so cheap?? Let’s get into it!

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The KZ ZSN Pro are a hybrid design IEM featuring a single dynamic driver and a single balanced armature. KZ calls the dynamic driver a “double magnetic dynamic”, although don’t be confused by the name they do appear to be a single diaphragm driver. Although KZ claims these offer sound equivalent to that from a 13mm-14mm driver these are just 10mm.

The physical construction of the earpieces is a mix of a resin body, zinc alloy outer cover and aluminium vocal cavity. This is a rather premium-feeling IEM despite its tiny price tag. Weight is 7g per earpiece without tips. They also come in 3 colourways, the smoked grey I have here as well as cyan and pink.

Cable connection is a 2-pin 0.75mm method. The particular connector that KZ uses is semi-recessed. This is what KZ call their ‘C-PIN’ connector. I quite like this connector, it’s easy to fit and stays connected well.

The stock cable is about as good as you might expect for such a low priced IEM. It’s not the most flexible and the ear hooks are pretty stiff, but I’ve seen worse, I think the stock Blon cable is marginally worse. Annoyingly there is no chin bead, I do prefer to see that with IEM cables for comfort reasons, however, a silicone o-ring makes an acceptable analogue for a bead. The version I have here has an inline mic for phone calls but you can also choose to buy them with a standard cable without the mic.

They come supplied with 4 pairs of silicone tips. 1 medium-sized pair of regular silicone tips and 3 pairs in small, medium and large of sizes Starline tips which have little grooves at the end. However, I purchased these from the seller Wooeasy on Ali Express who included 4 pairs of foam tips as a “gift”. I did most of my listening using the foam tips for personal comfort and fit preferences.

Comfort for me was much better than I had expected. The shape fits in my ears quite well and I had no issues with the ear hooks.

I also purchased an upgraded cable to go with these earphones. The KZ silver plated upgrade wire. This is a little more flexible than the stock cable, although the ear hooks themselves are just as stiff. Honestly, the difference between the stock cable and the upgrade one is small, so whether it was worth it or not, I’m not so sure. The box for the upgrade cable does say “Obvious improve the mids treble frequency audio performance of headphones”. Well, I’m not so sure about that, I didn’t notice any difference and nor have I ever with any IEM cable. Far more important is the look, feel and comfort and lack of microphonics of a cable. This one is an upgrade on the original but that’s a low bar to pass.

KZ claim they provide up to 26dB of isolation and I’m not sure how that compares to other earphones. But to my ears, I think these are pretty much average, not the most isolating I’ve heard but they also don’t sound open.

Also, these are super easy to drive at 24 Ohms impedance and an incredible 112dB sensitivity. I was worried I was going to destroy them with my O2, I could barely turn the amp up before they were getting too loud. In fact, it highlighted some channel imbalance issues at extremely low volumes on the O2. This is of course pretty normal in many headphone amps to get some channel imbalance at the very start of the volume pot. But it’s a good highlighter for just how sensitive they are.


Let’s move on to the sound section. And a quick disclaimer, budget-fi earphones are often known for unit variance. That might be the case with the ZSN Pro although I didn’t find much chatter online about this. But this is my experience with this one specific pair of ZSN Pro.

Also, I should state that all listening was done with foam tips because as usual I really struggled to get a good fit with the stock silicone. I just do not get on with silicone tips at all.

With that said…

Imaging ain’t bad and soundstage is somewhat intimate.

In terms of the overall sound signature, it’s warm and bright. So a somewhat V-shaped sound I suppose.

Bass has a decent extension, I could hear down to around 27-30Hz before I noticed it roll-off. It’s not overly boosted in the sub and low bass but there is a bit more energy in the mid and upper bass region. This makes them much warmer on the whole than the Tin T4 and perhaps suffers some bleed into low mids. I don’t mind a warm low end when it’s done right but my main issue with the bass region is in a lack of detail. This is not a particularly articulate or quick bass. Although I did find the ZSN Pro quite enjoyable for EDM, they don’t completely lack slam capability, but I fear a lot of the low-end detail is overpowered by the upper-frequency brightness.

Mids are not my cup of tea. Apart from the warm lower end which I don’t mind too much, the huge rise from 1kHz up to what sounds like a massive peak at 5kHz is more than a little shouty for my tastes. Upper mid and low treble glare or shout doesn’t seem to be uncommon for a lot of IEM’s. I believe a rise at 5kHz is required for a pinna gain type compensation. You also hear a similar rise on the Tin T4, however, the ZSN Pro just goes too far here.

The result is many vocals and instruments, and snares sound overly bright, shouty or sibilant and harsh in this region. A good example is the alto sax on Moanin’ by Charles Mingus which was so far forwards that it was way out of balance with the rest of the track. Coupled with a rather back of the mix and indistinct bass, I don’t think I’ve heard a worse reproduction of this track. For EDM tracks like Polaris by Deadmau5 they do fare much better but there is a lot of energy in the synth lead that is, unfortunately, a little too much and I found myself having to turn down the volume which further obfuscates the low end. So whilst this may be a somewhat v-shaped sound, unfortunately, the balance is way off. Although I did enjoy Hotel California by Eagles, the 12 string has a decent shimmer or sparkle and percussive hits have good energy but the low end could have used a bit more definition.

During the delayed guitar section towards the end of TalkTalk by A Perfect Circle, I found this to be bright and steely. I think blurry is a word I would use, there is simply a lack of definition here.

Treble is a bit grainy and lacking in detail. Treble drops a little after the peak at 5kHz but it still remains rather elevated, especially compared to the Tin T4. This elevation is also quite extended into the upper treble and air frequencies. As a result along with the upper mid shoutiness, this is a really rather bright headphone, despite the elevated bass.

All that might seem like a harsh judgement of a £10/$20 IEM. I suppose for sub $20 the KZ ZSN Pro aren’t too bad and on technicalities, they are about as good as one could expect for the price. But it’s the tuning that seems way off to me. Whilst these could have had a fun v-shaped sound signature, the low end is unable to counterbalance the upper mid forwardness and treble energy. For my tastes at least, I find them lacking in so many areas I don’t feel that I could personally use these even casually. For those that like a forwards sound signature, and enjoy the 5kHz energy, this is probably the budget-fi IEM for you.

However, for me, despite their insanely low price tag, I’m going to have to give the KZ ZSN Pro a miss.

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