Knowledge Zenith Zs-6

First off, a heart-felt thank you to George and Gearbest for providing these headphones. New gear is always fun and the opportunity to try out gear as it comes to market is indeed a privilege.

The Zs6 arrived in a typical manila padded envelope. The box is similar to the familiar KZ box with the black cardboard back and the transparent front but is a bit more upscale. It is now white with a slide off cover with graphics on the front and specs on the reverse as shown below. The transparent front displays the earpieces and a large KZ logo in a display tray with the cables etc. hidden behind. The display shows a very good-looking earpiece with three screws holding the side plate on instead of the normal glue. At first glance, the build quality seems a step above the expectation for KZ.


In a word, typical. Again, those of us that have bought KZ before will know the typical what comes in the box. It consists of a cable, 3 sets of tips in small, medium, and large, and a brief manual. While this has come to be expected, I had hoped with the step up in the IEM itself for KZ, the cables etc. would receive the same upgrades. This does not appear to be the case as no additional tips, cables, or accessories are provided in the box.

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Build Quality:

Build quality is definitely a step above what I have seen from KZ before. The aluminum is anodized evenly with no visible gaps or discoloration. The screws are all snugged tightly but easily broken loose to dismantle them should you so desire. If there is a complaint on the build of the earpiece itself it would be that the screen on the barrel is pressed in rather than fitted. I am sure the glue will hold fine, but a machined part with the screen held in place would have been preferable (and probably a lot more costly).

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The cable on the other hand, is the same cable we have seen KZ use on all their removable IEMs to date. The wires themselves seem to be coated in an almost plasti-dip rubber coating which does help keep noise down but also is borderline sticky. The two pin connectors are well marked L and R although the front and rear pin position (in phase/vs backward) is less immediately identifiable. They also retain the overly stiff memory wire from previous versions which I usually go about removing with a needle nose plier and a razor blade. The Jack is a 90-degree L shape and is a welcome sight as it is my preference vs the straight model.

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The microphone worked well for making calls and didn’t pick up a lot of extraneous noise. It did suffer from the same issues with wind and rubbing on clothing as you walk that pretty much all in-line microphones do. My personal preference is for cables without the microphone but I’m sure others will find it useful.



Treble: I put treble first in this review which is not my usual sequence but it is the first thing you notice on the Zs6. The treble is over-stated pretty substantially in the 8-10kHz range. I find that I need to adjust the graphic EQ on foobar down 6db at 8kHz and 8db at 10kHz to help tone down what can only be described as a hot treble. Once tuned a bit, that extra treble does have good extension and plenty of sparkle. Cymbals are lifelike and well detailed and the flute on Jethro Tull’s pieces was very well rendered. Without the EQ adjustments, the cymbals tend to take on a metallic sound and the flute loses the softness Ian Anderson was known for. Those who love a treble forward IEM will truly revel in the Zs6. Those who like good treble extension and lots of detail will enjoy the Zs6 too, it just may take a few attempts to get the EQ setting where you want it.

Mids: Once you get past the treble, you are rewarded with what I think is easily the best sounding IEM KZ has made to date. Mids are well rendered. Instrument separation is good, and presentation is more open than most. Soundstage isn’t huge, but isn’t claustrophobic either. Vocals are particularly susceptible to poor recordings and it would be easy to blame a lot on the IEM if you are not careful in selecting well mastered and well recorded tracks. The Zs6 is not particularly forgiving of poor source material.

Bass: This is where I think the Zs6 really shines. It is not the typical consumer oriented, bass boosted, beats-esque pattern we hear so frequently. Bass is tight and present in proportion to the rest of the sound signature. Again, it would be easy to say these didn’t have good extension or slam if you chose the wrong source material as they don’t seem to add to what the recording presents. I had to listen to some older EDM to really test out the bass as a lot of the predominantly guitar tracks I listen too didn’t provide enough bass-line to really study what the Zs6 was doing. The walking bass line at the start of Duran Duran, A View to a kill became one of my test tracks for this reason. Sub bass is present in good quantity and is controlled better than expected as it didn’t tend to get sloppier as volumes increased as is a common problem.


My first thoughts were that the piercing treble was going to keep the Zs6 from being something I could listen to for very long, but once EQ’d a bit, I must admit the Zs6 has enough detail and balance that I found myself coming back to them. They are really very good, except for that one treble spike. So, I began to look for ways to correct it.

First came the cable upgrade. I went to one of the silver replacement cables available on amazon as I had read from another head-fi member that he suspected the cable might be at fault for some of the issues with the sound. I can say that I don’t believe the cable made a bit of difference in the sound but I do like the microphonics of the new cable better so it will stay.

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Next came tip rolling. I tried JVC Spiral dots, Comply Foams of two types, Rebound foams, spin-fits, and a mix of other KZ tips I had from previous purchases. All made some difference and when coupled with the EQ adjustments the Comply foams gave the best combination of comfort, isolation, and sound signature. The worst went to the spiral dots which actually managed to make the Zs6 sound even brighter than it already was.

Then the Ostry tuning tips (OS-100, OS-200, OS-300) I had ordered to test with arrived from amazon. This series of tips going from blue to red to black introduces a filter in the barrel of the tip that cuts sound in certain ranges by as much as 6-7 db as seen in the chart below.


To my ears, the OS-200 tips allowed me to make the same correction I had previously made with the EQ with the tips and for those who are extremely treble shy, the OS-300 really brings that spike down. My go to tip for the Zs6 is the Comply foam or OS-300 as I think it does the best job of leveling the sound signature and gives the Zs6 a very natural presentation. It doesn’t hurt that the size large Ostry tip is a bit smaller than the size large KZ tip too and is a better fit for my ears.

It should also be noted that the Zs6 is low enough impedance to work when run directly from a phone but to really get the most out of them, you really need to amp them a bit. I ran them on a Schiit Magni 2 Uber, a Millett Starving Student (Poor impedance match and not recommended), a topping NS1, and Fiio E07k amps. When I attempted to use the Zs6 with the Millett SSH, I had a low level hiss in every track that was extremely distracting. Since I don’t usually test IEMs with this amp, I traded out a few other sets and found that most likely it is an impedance mismatch for anything below 32Ohms as it produced that same hiss with several 16Ohm high sensitivity IEMS. The Schitt Magni was a good pairing with the Zs6 and really helped open up the mids.


Inevitably these are going to draw comparisons from the other products by KZ as well as other products in the similar price point. I have attempted to compare them with some of the other IEMs I have in my collection that fit one or the other of these criteria.

Senfer DT – the Senfer fits the class as it is a dynamic/BA hybrid with a sub $50 price tag. The Senfer suffers from some of the same issue as the Zs6 in that it needs EQ to do its best. Unlike the Zs6, that tuning is pretty heavy rather than just a slight dip of the treble knob. The Senfers also suffer from bass bleed into the mids and just cant muster the level of detail or the bass extension shown by the Zs6.

Mee Electronics M6 Pro – These fit the comparison only in that they are roughly the same price point. The M6 pro is a single dynamic driver with what I have to call the most analytically correct but boring sound signature of the lot. If you want an absolute analytical piece of equipment – the M6 pro is for you. If you are looking for a sound signature with any sparkle and life to it at all, you’ll find the Zs6 way more interesting. The Zs6 also seemed to be able to pull more detail out of the same DAP and flac file when compared to the M6pro.

KZ ATE – This is probably the headphone in the KZ line that started it all for most of us. The ATE was super hyped as punching way above its weight and being priced at sub $15. While some of the hype was just that, a lot of the praise lauded on the ATE was deserved. Unfortunately, the ATE has now been through a series of manufacturing changes and may or may not be the same model people came to love. On its best day, the ATE is still not capable of the treble extension of the Zs6, nor does it render detail nearly as well. As much as I love the ATE and it is still one of my recommended cell phone replacement headphones, it isn’t going to compete with the sound signature of most multi-driver in ears.

KZ ZST – KZs first dual driver IEM. The Zst has become a daily driver for an awful lot of us and is an extremely good value. That is not to say it is without flaws and a treble that is over-stated is one of them. The Zst manages to provide a very nice sound signature if a bit treble forward but does not have the sparkle, depth of sound stage, or bass extension of the Zs6.

KZ Zs5 – My Zs5 is the Version 1 with a single BA driver in the nozzle. I state this up front as my musings may not apply to version 2. The Zs5 has a similar signature to the Zs6 once the EQ has been applied to the treble on the Zs6. Having said that, similar doesn’t mean same. The bass clarity is not quite as good on the Zs5 and the extension on both ends is lacking when compared to the Zs6. Soundstage is a bit more crowded on the Zs5 as well. This is not to say the Zs5 is a bad headphone, it is far from it, just when directly contrasting it to the Zs6 it begins to show the evolution of the design.

Urban-fun hybrid – The urban-fun has been my recommendation for a good near neutral sound signature in the sub $35 range. I still think these are a solid recommendation in that space and they do have a more neutral signature than the Zs6. They don’t present the level of detail of the Zs6, nor do they have as good treble extension. Bass quantity also goes to the Zs6 as the urban fun just cant muster as much slam on bass heavy tracks.

One More Quad – Ok, so these don’t fit the price comparison. I add them here as this is another story of a company bringing out several headphones that punched above their weight (Pistons anyone?) and then creating a more upscale branding and product. I think we can draw plenty of parallels between the Xiaomi/One More and KZ when we look at Pistons vs the ATE and then the One More triple and quad vs the Zst, Zs5, Zs6 line. Granted the two brands are at different points on the curve, but we can see enough parallels to suspect we might know where KZ will go next. The Quad is a big deep V sound with good extension on both ends and a lot of detail in between. The Zs6 is a bit shallower profile but lacks a bit of the refinement in the sound signature of the Quad. If there is one thing the Quad could learn from the Zs line, it has an un-natural transition between the dynamic and the lowest of the BA drivers that can result in an incoherent sound. It doesn’t show up often, but when it does, it can’t be ignored. Truthfully, I don’t think the Quad is $150 better than the Zs6 and with that being the difference in asking price, I’d be hard pressed to recommend the Quad when you could buy 4 pairs of the Zs6 and have one of each color and a spare (or a few extra cables and tips) for the same money.

The Zs6 is an evolutionary step from the Zst and Zs5 and won’t surprise people who are familiar with the line. It does some things better, which shows KZ is learning and listening and it hints at things to come. At this pace, the Zs9 might just be ready to compete with the Shure 846 and the Westone w60. That is possibly the best news of all because it means price competition in the market and we listeners are the ones who win. In the mean time, if you haven’t listened to a KZ lately, give them a try. You’ll be surprised how much sound quality $50 will buy these days.

PS> Had a question on which Jethro Tull tracks I used – Hunter Girl and Locomotive Breath.

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