● Integrated 2 dynamic unit and 2 balanced armatures units for each side earbud, provide wider frequency range and more abundant sound details.
● 7 - 40KHz super wide frequency range, offers board sound field and captures more abundant sound details, immersive sound effect.
● Aluminum alloy metal shell, professional grade electronic frequency division.
● Detachable design, easy to assemble and convenient to maintain, satisfies various demands on lines as well.
● 3.5mm gold-plated L-bend jack, compatible with the majority of electronic devices, like phones, computer, walkman, MP3 and so on.
● Built-in thin iron wire in cord, you can wear it and hang on your ear so as to avoid falling or dropping while doing sports.
● High definition microphone supports clear and smooth conversation.
● On-cord control, easy to pause / play music, switch songs and answer / refuse call, adjust volume. Specification General
Pros: 1) Less treble than original ZS6.
2) Paint is actually good this time. Definitely better than what they've used several years ago.
3) Still good soundstage/separation.
They sound... big?
Cons: Mids, bass and everything else is as subpar as it was before.
Fatiguing sound. It's not only about the treble, mids are fatiguing too.
Not bad, but not good also.
It's like a perfect example of an old school Chi-Fi sound.
Lots of drivers with strange/mediocre result.
New version is basically an upgraded version of the old ZS6s.
Less treble fatigue, better balance overall.
Not worth $50 in today's market.
For those of you that are unaware, there is a quiet storm taking place in the IEM (and Audio Gear) market which we hobbyists affectionately refer to as Chi-Fi (Chinese Fidelity). In essence, the sound quality of audio gear coming from some Chinese manufacturers (Knowledge Zenith, Fiio, Monoprice, Shanling and others) is improving and progressing at a quickening pace. Some brands deserve as much attention as the established brands, if for no other reason than the value proposition in what is quickly becoming an unavoidable global economic downturn (where one typically receives less for their hard earned cash). In the midst of said global economic upheaval, KZ Acoustics is a manufacturer that consistently offers exceptional value for your hard earned cash and the ZS6 is evidence enough that the changes in the world of audio gear are reaching a feverish pitch.
Before we get into the review you should know upfront that I own and enjoy several of KZ's hybrid IEMs (ZST, ES3, ZS5(v1) & ZSR) and I have no issue with the treble present in any of these models. I am a micro-detail junkie that enjoys a bright sound signature IF......IF there is enough weight and density present in the midrange and lower extremities. I mention this because those of you who are sensitive to forward treble would be wise to keep in mind my preferences and properly absorb this review through the filter of your own preferences.
I tend to prefer a relatively neutral sound signature with a slight emphasis in both bass and lower treble, which is basically a mild "U" shaped sound signature where midrange frequencies are left intact and unaffected. I find that an absolute neutral sound signature usually lacks enough energy for the genres I enjoy most, which are Classic Trance and Progressive (early Tiesto, Markus Schulz, Otello, DT8 Project), Chill Out, Breakbeat (Hybrid & Burufunk Remixes) and 80's & 90's (New Order, Secession, The Cure, Siouxie & The Banshees, Depeche Mode). Sure I listen to Verve Remixed, Sade, Bach, Ella Fitzgerald and everything in between, but as of late the bulk of my listening pleasure is focused on the aforementioned genres.
Take note when you read IEM reviews that when the reviewer gives his/her opinion regarding the sound that there are many factors that shape the final sound an IEM delivers to one's ear.
Those factors include:
1 - Shape & size of reviewer's ear canals. (shallow/deep, wide/narrow)
2 - Shape & size of eartips (round/cone, single, double or triple flange)
3 - Materials of eartips (silicone/foam)
4 - Shape of IEM (and/or angle of nozzle) can cause fitment issues for some.
5 - Source (quality of DAC in smartphone, laptop, digital audio player)
6 - Source (power rating) is it amplified/unamplified.
7 - The IEM itself (driver flex/trapping air in canal causing muffled sound.
8 - The Reviewers ability to hear all frequency ranges (age plays a factor).
Most consumers are unaware of how much weight each of these factors hold in rendering a final verdict. This is why there is such a wide variance in not only ratings, but the description of an IEMs sound. An unaware consumer purchases a perfectly fine IEM but has difficulty keeping the IEM in the ear or he/she does not satisfactorily seal the ear canal with the included silicone eartips (this is a common occurrence) and the consumer summarily dismisses the IEM as sub par. Another consumer purchases the same IEM but experiences a perfect fit and seal and has nothing but praise for the same IEM. Sealing the ear canals AND HAVING THE EARTIP FIRMLY AFFIXED to the IEM nozzle is the only proper way to use in-ear monitors. I can think of no audio equipment that is subjected to such praise or ridicule as the in-ear monitor. As if that's not enough, there is no "one-size-fits-all" when it comes to IEM eartips.
Materials (silicone/foam) have different dampening effects on final sound.
Shape of the eartips (olive-shaped, cone-shaped or other-shaped) can have different dampening effects on final sound based on how much space is between the IEM nozzle and your eardrum and how well the eartip has sealed the ear canal.
The aperture of the eartip's opening (wide-bore/narrow-bore) will have dampening effects on the final sound.
The easiest way for you to experience the different effects I am discussing is to take your current on-ear headphones or over-ear headphones, pick a song full of energy, put the earphones on and let them sit naturally over or on your ears. Listen to the music for two minutes. After two minutes, using your hands, slightly press the headphones closer to your eardrums. Notice the change in the sound. Is there more/less bass? Is there more/less treble? Did the vocals slightly slip forward/back?
Consider that on-ear and over-ear headphones have a driver that sits approximately 1 1/2 inches to 2 inches from your eardrums and by pressing the headphones 1/4" closer to your eardrums the sound changed. Now consider that an IEM driver sits anywhere from 3/4" to 1/4" from your eardrums and the slightest changes (angle, depth, shape, material) can have up to three times more of an effect due to the proximity of the IEM to the eardrum.
For this reason, I think it is wise to invest a nominal dollar amount on different eartips to find an eartip that works well for your particular ear's anatomy. This way you experience everything the earphone tuner intended for you to experience. Some IEM manufacturers supply multiple sizes (S/M/L) and/or materials (silicone/foam) of eartips to increase the odds that the consumer achieves a satisfactory seal, but even this is not foolproof. If this information holds any interest for you, there are a plethora of aftermarket eartip brands to look into, such as "JVC Spiral Dots", "Spinfits", "Comply Foam Eartips" or "Znari Foam Eartips", "Creative Aurvana" and others. If you really want to fine tune things, then you might find yourself doing what I do, which is scouring Amazon for inexpensive earphones that appear to have silicone eartips that have a shape that typically work well with my ear's anatomy.
The Knowledge Zenith ZS6:
When Knowledge Zenith released their single dynamic driver ZS3 "with detachable cables" in June 2016, there wasn't much in the sub-$20 category that could touch it's sound quality and comfort (so long as you knew how to moderate the bass response via eartip size).
Several months later KZ ventured into the hybrid market offering their impressive and well received budget-friendly ZST (a 1BA & 1DD model with detachable cables) which, at the time of it's release, nearly dwarfed everything else in the sub-$20 price bracket.
All of Knowledge Zenith's earlier models (ED3, ED7, ED8, ED9, ED10, EDSE, EDR1, EDR2, ATE, ATR, HDS1, HDS2, HDS3, DT5, DT3 and others) were dynamic driver IEMs in the sub-$20 price bracket and several of these models deserve your attention if the ZS6 at $48 is too steep for your budget at this particular time. I have included links to several reviews of said models here on Head-Fi that can help paint a clearer picture of a KZ in-ear monitor that might cater more to your particular preferences.
KZ Acoustics is the trailblazer; they lead the way on what can be achieved by pushing the envelope in price-to-performance offerings.
In this instance KZ Acoustics is the first manufacturer to market with a quad-driver in-ear monitor below not just the $200 threshold or even the $100 threshold. No KZ has offered the ZS6 at below the $50 threshold.
The ZS6 is a dual dynamic driver (10mm & 6mm) AND dual balanced armature hybrid in-ear monitor for. $45+/-!
You read that correctly; $45 for a 2+2 hybrid IEM!
Prior to the ZS6's release (actually the ZS5's release) the minimum entry fee for a quad-driver was $200 (1More Quad-Driver) but KZ's ZS5 and ZS6 opened the floodgates. Now the marketplace is awash with sub-$50 quad-driver IEMs from a growing number of manufacturers that are planting their stake in the ground in hopes of establishing a name for themselves. That's all well and good but my suggestion is that we take a moment to reflect on which company actually cast off the shackles of conventional thinking to bring you far better sound at a far better price.
Still, looking back at KZ's previous offerings $50 is quite a jump in price from $20 and it just begs the question:
"Should Knowledge Zenith be venturing into deeper waters?"
Sure, they've churned out dozens of great sounding single dynamic driver IEMs and several dual dynamic driver IEMs but is it somewhat optimistic of KZ to include their wares in higher IEM tiers or should Knowledge Zenith just continue doing what they've proven to do better than just about any other budget IEM manufacturer, which is to CONSISTENTLY offer the best "bang for buck" IEMs in a landscape littered with "hit or miss" budget-fi IEMs from East Asia?
Let's start at the beginning and take into consideration that the ZS5 was KZ's very first budget-minded 2+2 hybrid IEM to hit the market. As a devoted fan of Knowledge Zenith, I won't hesitate to tell you that I was notably disappointed that KZ offered their flagship model (ZS5) in a PLASTIC shell. It later became clear to me that the ZS5 was more likely a beta model; a stepping stone to the beautifully crafted and rich sounding ZS6.
Yes, the ZS5 and ZS6 shells may enclose similar hardware but to my ears they offer very different presentations. A 2+2 hybrid design is a much more complex endeavor than KZ's more simple 1+1 hybrid design (ZST) and one wonders if the sound engineers at KZ have the skills to properly tune such a complex design? A good number of dual dynamic driver IEMs have earned the reputation of sounding .......well, muddy; meanwhile many hybrid IEMs have earned a reputation of sounding somewhat incoherent due to two completely different technologies at work yet sharing the same space. Is KZ capable of bucking the trend? If the answer to that question is no then this could go very badly for KZ. Most of KZ's detractors and even KZ's fans would quip hat KZ should stick to the $10 budget bin and if the answer to that question is yes then the more logical question is "will more drivers automatically equate to better sound?" Let's find out just what the mad scientists at KZ Acoustics have been up to.
My Rose Red ZS6 has a beautifully crafted CNC aluminum casing with a full aluminum nozzle (no signs of cheap plastic). The faceplate of the ZS6 has three vents and a quality mesh grill just beneath said vents to keep dust and grime from getting in whilst allowing the music to breathe. The three torx screws that affix the faceplate to the main body allow easy access to the ZS6 inner components if I need access to them. It's all very well done!
I wholeheartedly applaud KZ for including the option for easy access because it allows me to experiment with different modifications. I have considered opening one of my ZS6's to reposition the BAs so they fire into the main cavity of the ZS6 instead of firing directly out of the nozzle. I'm hoping this might temper extension and perhaps soften the analytical nature of the BAs while increasing soundstage via diffusion and reflection of the treble. We'll see, right?
Later, we'll take a look at an actual modified ZS6 by the KZ Thread's very own "Slater", so the treble-sensitive among you should find that informative and helpful.
I am particularly disappointed in KZ's choice of cable for what was once their flagship IEM. The included cable was specifically designed for the KZ ZS3. I saw fit to upgrade the fable on my ZS3. What on earth was KZ thinking in offering something so pedestrian with something as polished and upscale as the ZS6? Note the angled step down moulding below the "L" & "R" markings on the cable connectors. Those angles were designed specifically for the KZ ZS3. At any rate, I recommend KZ's Braided Silver Upgrade Cable (4-core transparent) with the 3.5mm jack or the 8-core Braided Silver Upgrade Cable that you see attached to my ZS6. I will give credit where credit is due by saying kudos to KZ for choosing to stick with the 2-pin cable design instead of the MMCX cable design. MMCX cables may be more common but I believe the 2-pin design is a more reliable connection less prone to interruption as MMCX connections can sometimes deteriorate.
The ZS6 comes with KZ's exclusive Star-tipped Silicone Eartips (S,M & L) which affix firmly to the ZS6's aluminum nozzle but be aware that earlier models of the ZS6 have no lip to keep the eartip from sliding off. A Q-Tip and a pinch of hydrogen peroxide can be employed from time to time to dissolve the earwax that tends to cause slippage.
There has been much praise of the ZS6 sound signature when the ZS6 is paired with foam eartips. I have Znari Foam Eartips and Comply Foam Eartips but I just can not abide the dampening effects present in foam eartips because I always feel one step removed from the music. Don't let my preferences deter you because many people find foam eartips to be a much more comfortable fit. In fact, many people prefer the foam eartip's ability to smooth out the analytical and sometimes cold nature of balanced armature receivers. Indeed, many people swear by foamies and use them exclusively but to my shallow ear canals their is a slight loss of definition to everything portrayed from top to bottom (bass, vocals, treble, etc.). In other words, for me, foamies smooth things a little too much. Instruments and vocals tend to lose their etched definition by a slight degree and for me that slight loss is unacceptable because an instruments definition needs to be true to a fault. Conversely, silicone eartips ALWAYS give me a presentation that I deem "true" to the music and "true" to the IEM. To my ears, the best silicone eartips for the ZS6 are KZ or Tennmak Whirlwind eartips but said eartips are not included. In light of its near $50 pricetag, KZ should be including their own Whirlwind eartips (S, M & L) with the ZS6. In fact, I'll go one step further and say that KZ should be including three variants (Star-tipped, Foam and Whirlwind) to give the consumer an optimal chance for a satisfactory experience with their flagship IEM.
My general rule of thumb when it comes to IEMs that sport multi balanced armatures is to use a low output impedance source with a well regarded DAC and sufficient power. Though the impedance of the ZS6 is 16Ω it still sports not one, but two balanced armatures and two dynamic drivers (6mm & 10mm)
Having multiple balanced armatures can sometimes introduce impedance curves and/or render an IEM quite sensitive to your source (phone, laptop, DAP, etc) so keep in mind that if your main source is a power-efficient smartphone you may find the ZS6 to be quite bright. If your phone isn't tethered to a low impedance portable amp or equipped with an exceptional DAC then a single dynamic driver IEM like KZ's ZS3 (warm), EDR2 (more balanced) or ED9 (bright and airy) may be a better combination/pairing with your phone. I suspect that a fair share of the complaints of an unpleasant treble spike on the ZS6 may be due to ill pairings. You'll get the best out of the ZS6 when it is paired with a warm-leaning DAP. You will also find that a great DAC and more power will likely give you a smoother response. It's not a hard and fast rule, but I find it to be true more often than not.
I would describe the ZS6 in stock form as an IEM that excels at presenting micro-details and definition in treble, midrange (vocals) and bass all at once. You will hear "everything" that was recorded and you'll hear it in HD! A poorly mastered track will be shamefully exposed while a well mastered track will sound incredible.
I made a minor modification to my ZS6. I removed the red nylon screens from my KZ ZS3 and centered them directly on top of the ZS6 metal screens. This softened the analytical nature of the BAs giving my ZS6 a sound signature reminiscent of a well-tuned single dynamic driver. Instead of being full-bodied in the lower frequencies and highly analytical in the higher frequencies the coherency was astounding from top to bottom because the "body" of sound was uniform from 16hz - 16,000hz (my hearing range). I sampled the ZS6 for 6 uninterrupted hours with various genres .....zero fatigue!
Let's isolate and address the more substantive frequency ranges.
To put it succinctly, the ZS6's bass is clean, tight and natural with admirable texture in both mid-bass and sub-bass.
......yet quite authoritative.
The balance of sub-bass to mid-bass is well-judged at nearly 50/50. The music was flowing and alive regardless of the genre I listened to.
My best description would be a velvet hammer because the bass hits hard but doesn't obscure the other frequencies. Typically, big bass can mask higher frequencies and/or force the midrange into submission but this is not an issue for the ZS6. When pairing the ZS6 with Tennmak's whirlwind wide-bored eartips I thought the lower frequencies might lose some impact due to diffusion but they still came through with excellent presence and weight. You need to hear how resolving and clean the sub-bass is?
It's hauntingly flawless on demanding tracks like Solarstone's take on "Center Of The Sun".
Want to hear how deep your ZS6 will dig? Push play on "Imagine" below and be amazed. I should mention that on my smartphone the track's bass is deep but slightly loose; on my Fiio X3(i) it is exceptionally clean and deep.
For composure, let's test two tracks. The first is a recording of an epic metal track that had only mediocre mastering. The drums are in double time but you can still pinpoint both lead guitars chugging away separately. The second track has better mastering (superior separation and imaging) but the ZS6 possesses the ability to cleanly pull and separate the details on the first track with no loss of composure in the presentation.....despite the mediocre mastering.
Why am I so enamored?
The ZS6 is only $40+/-!
The first track to showcase the ZS6's midrange is Tracy Chapman's remastered "Fast Car". Remastered tracks aren't always "better" but the 2015 remastered "Fast Car" sounds much more dynamic than the standard recording. The ZS6 neatly unpacked everything and put it all on the stage in my mind's eye . Tracy's vocals are forward, full-bodied and alive, refusing to be subdued by the copious bass.
James Taylor's "Fire and Rain" was just as vivid with great texture, presence and clarity. There were moments that I thought I might be hearing resonance but it turned out to be the cello's natural resonance rendered exceptionally well. It was lifelike; it was mesmerizing.
What about classical music?
It's a great compliment when I say that I felt as though I was at Symphony Hall witnessing Rudolf Serkin and George Szell make history recording one of Brahms' more complex piano concertos. The ZS6 captures the weight of the notes from the piano and the timbre of the french horns quite well.
J.S. Bach's Toccata & Fugue in D minor (BWV 565) is another perennial favorite but the ZS6's transparency will expose that the first sample lacks the depth of emotion found in the second sample. I absolutely despise the way the first sample was mastered but it is one of the clearest recordings I could find on YouTube that would serve our purposes here. You will hear how clumsy the recording engineer is. He completely butcher's the timing and flow of the orchestra by carelessly introducing strings and other instruments in a slipshod manner. For instance, between the 25 sec and 35 sec mark the Timpani/KettleDrum should steadily rise drawing you in just as the piece begins to unfold; the rolling of the timpani should evoke a strong sense of emotion here.....but it was not to be with this recording and the ZS6 lays it bare. Likewise, the outro of the introduction from 3 min 12 sec mark to the 3 min 30 sec mark the timpani/kettledrum should steadily rise and evoke a strong sense of emotion........but it does not.
Now, hear a proper recording of the same piece. From the outset you are drawn in and willingly held captive until the piece closes. The ZS6 sets the table neatly so you can focus on the feast set before you.
The ZS6 presentation is clean enough that it affords one the ability to hear the slightest nuances of a given recording. Plainly stated, I loathe the former sample and champion the latter.
Moving on, can there be intimacy in a more complex metal track?
Yes, but metal recordings tend to range from cacophony to sublime perfection.
It's real and present with FlyLeaf's ode to being alive in "All Around Me". Sturm's vocal range and coloration is well suited for folk or bluegrass genres but through the ZS6 you can hear how she pulls no punches here. There is good presence and decent weight but the ZS6 shows how the vocals go form slightly recessed to slightly forward during the recording.
This is the section that the treble-sensitive are positively raising hell over. Some simply can't handle it.The ZS6 treble focus is on lower-treble to mid-treble. It is forward though not sibilant to my ears. On some tracks like Toni Braxton's "He Wasn't Man Enough For Me" the treble was a bit aggressive and I had to turn the volume down a couple of notches but the sense of air and transparency is exceptional. If you are treble-sensitive you should probably skip this sample because the recording is exceptionally clear with a fair amount of energy up top and the ZS6 delivers it with open arms.
If you just listened to the above track and it was a bit too much for you then please be aware that it is common practice to wear foam eartips with hybrid or balanced armature IEMs to soften the BA's analytical nature. This is not something that is applicable to one manufacturer, it is common practice when using BA in-ear monitors. Most of you should be considering foam eartips for the ZS6 because, again, you'll find that foam eartips will absorb the occasional aggressiveness on some of the recordings in your music collection.
Diana Krall's "I Miss You So" and "Maybe You'll Be There" are tracks that are prone to sibilance but I experienced none with the ZS6. Both tracks were presented with excellent micro-detail while the midrange seemed almost forward in the mix. The treble does not overpower the midrange. The presence of Krall's voice has your full attention.
Before moving on I think it would be wise to point out the ZS6's unforgiving nature. Sometimes recordings are mastered with shouty and unrefined vocals and consequently the presentation of such recordings can be somewhat of a mixed bag. You may not enjoy the end result if you couple the ZS6 to a bright-leaning DAP in the hopes of enjoying recordingsthat display scratchy or strident vocals. The upper-midrange will be somewhat raw and unrefined because the recording is somewhat raw and unrefined.
To put things into perspectiveI'be included several samples of what to avoid with the ZS6. You'll hear the flaws.
It's really a pity when you consider that recordings of this caliber were recorded nearly 40 years earlier. 40 YEARS!
Soundstage and Imaging:
The previous 2+2 model, the ZS5(v1), sound airy and detailed with a wide soundstage. The ZS6 soundstage is slightly different. The ZS5(v1) soundstage is more linear from left to right. I wouldn't say the ZS6 soundstage is more narrow, it actually has a different shape and is more diffuse. I find that the midrange on the ZS6 sits a bit more forward giving the ZS6 soundstage more of a "V" shape. On the ZS5, the details that are on the periphery are as prominent as the vocals. On the ZS6, those same peripheral details slip back slightly. Yes, those details are still there; they just aren't as prominent because the midrange/vocals are more present. With the ZS5 you are on stage with the band. With the ZS6 you are in the front row with the lead singer reaching for your hand while the band is just a few short feet away.
I should mention that my Fiio X3i does not have an equalizer. The Fiio X3i has a 10+/- treble adjustment and a 10+/- Bass adjustment. I don't like altering the sound via EQs but I did modify my ZS6 ..... with the ZS3 nylon screens. I bring all of this up because when I paired the blue whirlwind eartips you see in the photos with my screen modification, not only were the highs gently attenuated, but the soundstage widened a tad and the overall sound in general was a bit more cohesive. I would go so far as to say that my ZS6 does not sound like two different technologies (dynamic driver & balanced armature) at work, but rather a well tuned Dynamic Driver with a coherent and consistent body from top to bottom (16hz to 16,000hz) as opposed to the DD sounding full bodied and the BA sounding analytical. I find that my modification doesn't alter the sound exiting the source (Fiio X3i) but it redirects sound, via reflection, around the filters (nylon screens) resulting in a slightly wider soundstage. In my estimation the ZS6 is an in-ear version of the Superlux 668b over-ear full-size headphones, albeit with slightly more presence in the lower frequencies. That is quite a compliment in my book.
Comparison to the ZS5:
The ZS5(v1) is an epic IEM for $36, and although few IEMs in the sub-$40 price bracket could touch it at the time of its release, the lack of presence in the mids, it's dual personality (due to the lack of a crossover) and the secondhand cable shenanigans (square peg in a round hole) kept the ZS5 from being all it could have been. If you've read my ZS5 review, then you know that I considered the ZS5 to be a beta project for the ZS6. That said, most of its shortcomings have been addressed and rectified with the release of the ZS6.
In my opinion those shortcomings were:
The ZS5's plastic housing (the ZS6 is beautifully crafted aluminum)
Nonexistent crossover (the ZS6 has an active crossover)
Mids (ZS6 = creamy and present vs ZS5 = laid back and slightly recessed)
Bass (ZS6 = well judged; ZS5 = good but less agile)
Cables: Aside from being detachable, nothing special on either. Get an upgrade cable.
The ZS5 mids are more laid back and lack the presence and projection the ZS6 has in my opinion. The ZS6 mids seem more front and center though I find the ZSR's midrange to have a better sense of density.
I should also mention that the ZS5(v1) have a lower sensitivity than the ZS6. The ZS5=4.8Ω @ 1kHz while the ZS6=16Ω @ 1kHz. The ZS5 need more power to reach the same volume as the ZS6. On my Fiio X3i, with both the ZS5 and the ZS6 simultaneously plugged into a splitter, I need to increase the volume for the ZS5 when trying to match volumes. For instance a comfortable volume for my ZS6 is 17/60 whereas the ZS5 must be set to 21/60 to reach the same volume.
In comparison to the BGVP DM5:
The DM5 is a bit of an anomaly. If it weren't for the slightly aggressive 2500hz lift and the odd imaging the DM5 would have probably outperformed the ZS6. The DM5 has the uncanny ability to separate and cast instruments further out to the left and right leaving a gaping and unnatural void between the center stage and the outer stage as if the vocalist is centerstage while all instruments are at the stage's extremities. Everything is clean and clear but the positioning is just odd. I've no idea how BGVP achieved this but from time to time I have to revisit the experience out of sheer curiosity.
When the ZS6 was released there were very few IEMs in the sub-$50 price bracket that could touch it's price-to-performance ratio. Nine months hence and the competition is a bit more stiff with the introduction of the TinAudio T2 ($50), KZ's own ED16 and a handful of other one-hit wonders.
In my estimation the few Chi-Fi manufacturers that have the resources to compete and the capability to scale with KZ are UiiSii, Tennmak and perhaps KZ-defectors TRN.
UiiSii is still finding their footing with hybrids (notice their Hi-905 has vanished from the marketplace) and Tennmak charges nearly double KZ's asking prices while they seemingly remain stuck in second gear. I haven't seen anything new or noteworthy from Tennmak or UiiSii lately and it'll be interesting to see how things develop with TRN (who make excellent cables) but what will be even more interesting is to see where KZ goes from here.
It appears that KZ's sound engineers do possess the skills to properly tune a design as complex as the ZS6. The ZS6 is one of my favorite IEMs and I wholeheartedly look forward to KZ's future endeavors.They typically offer "entertaining" sound signatures and on rare occasions they attempt to offer a neutral sound signature. Sometimes a "neutral" IEM can be dry and uninspiring but I'd still like to see KZ release a well balanced and beautifully machined CNC aluminum IEM for the diehard and persnickety audiophiles. Sure, they'll howl and wail about how it doesn't compare to their $2,500 trophy IEM or they'll make patronizing remarks like "for its price" but let's be clear. Companies like KZ Acoustics, Fiio and a handful of others are bringing great sounding gear to the huddled masses at one tenth of what comparable gear would have cost you just a few short years ago. When they get it wrong they push forward. When they get it right they push forward. Every passing month brings more promise and my anticipation, though measured, remains unabated. If their goal was to offer up an in-ear monitor that delivers an improved presentation of my music while simultaneously offering me a thoroughly entertaining IEM then I hereby dub their endeavor a success.
If you were to ask me to define the ZS6 in one single paragraph I would offer the following:
KZ Acoustics ZS6 is a beautifully machined aluminum IEM with an anodized satin-like paint finish. The dual dynamic drivers (6mm & 10mm) in conjunction with the dual balanced armatures (mid-to-high & ultra high) offer up a highly resolute and spacious sound signature. The ZS6 separates each instrument and then give said instruments their own sense of space and positioning on the stage in your mind's eye. The presentation is somewhat akin to attending a performance at an amphitheate (vivid and defined imaging in an open and airy acoustic setting). The ZS6's beefy bass is well-regulated, it's glistening treble delivers every detail with poise & transparency while the midrange is neatly perched so as not to be ignored (despite the mild "V" shape sound signature). In summary, the $40(+/-) entry fee is almost comical when you consider that a hybrid of this caliber would have cost several hundred dollars just a few short years ago. In my humble opinion, the ZS6 is an absolute treasure that should not be overlooked if you're in the market for an entertaining set of in-ear monitors because times........ well, times are a changin' friends.
I can not close out this review without telling you that it took an inordinate amount of time for me to review the ZS6. It wasn't just because I was trying to pin this or that down; it was mainly because I simply got lost in the music. The ZS6 is a vivid and entertaining in-ear with exceptional layering, imaging, separation and detail from top to bottom. It's the very reason this reviewer owns several pair of ZS6's.
Given KZ's penchant for "adjusting" their IEMs with ne'er a whisper I wouldn't be surprised if KZ have quietly upgraded the ZS6 (current production only) with their newer graphene dynamic drivers and their newly refined 30095 balanced armatures. If the ZS6 is still being produced then I owe it to myself and perhaps to our community to order just one more pair of my favorite in-ear monitors to find out if this is so.
Resistance is futile.
Hope this was helpful.
p.s. - I'm still waiting for KZ to revisit the sound signature of their HDS1.
Now that you've got a solid description of what the ZS6 sounds like in its stock form let's take a look at what kind of magic Slater (our resident modifier) has worked into the ZS6 for the treble-sensitive enthusiasts. I would intimate that I, Slater and perhaps a few of the KZ veterans consider the price-to-performance ratio of the ZS6 to be so good that it should be enjoyed by as many people as possible. Those are my words and not Slater's or anyone else's but indeed Slater has furnished me with a sample of ZS6's that he personally modified for the treble-sensitive enthusiasts.
Our KZ thread here on Head-Fi is littered with feedback from users whom simply find the ZS6 to be too bright an IEM for them. Reliable FR graphs do illustrate the ZS6's aggressiveness particularly at the 10khz range. My own feedback regarding the ZS6's 10khz spike was recorded in my original review (above), though I have no particular aversion to it except on occasion. I find that less than 10% of the recordings in my personal music collection cross the borderline as "too aggressive" in the treble region. Pat Benatar's "Precious Time" album, Bruce Springsteen's "Born In The U.S.A." album and a few others can sometimes push the envelope but for me the ZS6 in it's stock form ticks nearly all of my "boxes".
For the treble-sensitive, though, the ZS6 upper frequencies may well be too aggressive. If you've been searching for a well-built and clean sounding IEM but you're a little gun-shy, due to reports that the ZS6 is a bit treble-happy, then this addendum is for you.
One of the KZ thread's most helpful contributors is a seemingly inexhaustible wealth of information about minor modifications that one can perform to shape the sound signature of a handful of IEM's more to one's own preferences.
"Slater" is one of our very own modification gurus on the Chi-Fi threads. Did you find the KZ ZS3 to be slightly boomy or was that Blitwolf sound signature slightly askew (not balanced enough)? Slater has offered up slight modifications to assist in cleaning up the sound signature on both of the aforementioned IEMs.
Recently, Slater posted some helpful information on how to successfully modify the ZS6 to temper the 10khz region for treble-sensitive users. On offer are two different modifications you can perform so long as you don't mind performing a little minor surgery on your ZS6. The first modification will be hereby dubbed the ZS6(sm1) and the second mod the ZS6(sm2).
I will be reviewing the ZS6(sm1) modification now and the ZS6(sm2) in the weeks to come so feel free to visit this review from time to time or follow the KZ Thread to keep abreast of any new and/or relevant information.
For consistency in volume I plugged both IEMs into a 3.5mm splitter and plugged said splitter into a Fiio X3(i). The Fiio X3(i) specs are as follows:
＞540 mW (16 Ω/THD+N＜1%)
Output Power 2:
＞270 mW (32 Ω/THD+N＜1%)
Output Power 3:
＞30 mW (300 Ω/THD+N＜1%)
20 Hz~20 kHz
＞105 dB ( A-weighted)
＞75 dB (1 kHz)
＜0.005% (1 kHz)
MAX Output Voltage:
MAX Output Current:
＞250 mA (For reference)
Both IEMs were tethered to the Fiio X3(i) with KZ's 4-cord silver plated transparent upgrade cables (with black rings). Thanks to Hakuzen's diligence we know that the impedance of this particular cable is
The ZS6 (Slater Mod #1):
The ZS6(sm1) modification was achieved by modifying both the mid-bass dynamic driver and the high frequency balanced armature. It is a work in progress and as things develop and get dialed in we'll provide further details on how to properly modify your own ZS6.
In the case of this "sm1" the result of modifying the BA is a very subtle but effective drawdown of the 8khz to 11khz range by about 2db. To my ears it sounds somewhat akin to how KZ slightly tempered the treble on their ZSR model. It is not an identical presentation to the ZSR's treble as the ZSR seems to offer a more natural presence. The ZS6(sm1) treble, while still present, sounds as though it is subtly softened when comparing it directly with the stock ZS6's treble. The difference isn't huge but it is noticeable and it will render the ZS6 more tolerable for the treble-sensitive who'd like to enjoy a fatigue-free listening session without sacrificing much of the ZS6's micro-detail.
One thing to keep in mind is that the ZS6 in it's natural state is an IEM that, due to it's triple-vented faceplates, presents everything as if you are listening to a semi-open set of headphones. I intimated this about KZ's ZS5(v1) but it is even more so with the ZS6. The ZS5(v1), despite it's more recessed midrange, is still one of KZ's best tuned IEMs to my ears (when coupled to a low output impedance source). Comparing the ZS5(v1) with the stock ZS6 one gets the sense that the ZS5(v1) has slightly more body across the entire frequency range. Unlike the ZS6's triple-vented faceplate the ZS5(v1) faceplate has no vents "on" the actual facia of the IEM. No, the vents on the ZS5(v1) are found precisely where the faceplate attaches to the main body of the IEM. The gap between the faceplate and main body of the ZS5(v1) was measured with precision; it was designed to give the IEM a full-bodied yet airy presentation. Some early reviews of the ZS5(v1) mistook the thin gap between the faceplate and the main body as poor workmanship or poor quality control. That's an understandable oversight if one approaches KZ's finished products with an instilled bias against inexpensive gear or if one isn't particularly the observant type but I find the vents on the ZS5(v1) are an ingenious design because they give the IEM a sense of warmth and openness all at once that really works in the ZS5(v1)'s favor. Again, the design of the vents lend an overall sense of extra "body" to it's sound signature. My hypothesis is that the ZS5(v1)'s solid faceplate is not only a full point of reflection but the material (plastic) tends to absorb a wee bit of the energy whereas the ZS6's metal faceplate absorbs less energy while the vented faceplates, in a sense, open a window. You can tell that the ZS5(v1) and the ZS6 are siblings but the triple-vented faceplates give the ZS6 a distinctly different sense of the presentation.
1) The instruments are positioned in a more linear fashion from left to right on the ZS5(v1). On the ZS6 the vocalist is positioned more toward the front of the stage while guitars, strings and percussion are positioned for a more supportive role. Guitars, strings and percussion do not sound recessed, necessarily, but in comparison to the ZS5(v1) you can tell that each instrument is positioned to give the vocalist more presence on the stage.
2) The triple-vents on the facia give the ZS6 a more diffuse presentation allowing the mid-bass and sub-bass to breathe and decay in a more organic way. The ZS5(v1) vent design may lend more body to each note but it's mid-bass and sub-bass lose some of the definition found in the ZS6 presentation.
So, why the dissertation, Doc?
Primarily to set forth in detail the nuances that separate the two siblings before making my proclamation that the ZS6(sm1) bass sounds more akin to the bass of the ZS5(v1). The ZS6(sm1) bass is full and present but the modification to the mid-bass DD renders it slightly less defined than the stock ZS6 bass. Slater and I have discussed how the mid-bass is effected with this particular modification and he has determined that perhaps it is best to forego modifying the mid-bass DD. However, if you're a fan of the ZS5(v1)'s less analytical presentation then perhaps modifying the mid-bass dynamic driver may be just what it is you're craving. The drawdown of the treble in conjunction with the softer bass response get the ZS6(sm1) closer to a ZS5(v1) sound signature though the soundstage will differ.
Oddly enough this modification in its entirety also effects the upper midrange. Apparently, the ZS6's high frequency balanced armature spans from 4khz to 12khz where both sibilance in the upper midrange is found and piercing in the lower treble is found. Modifying the high frequency balanced armature gently rolls the definition. You still get decent definition but it's different.
Listening to Sade's "Kiss Of Life" on the ZS6(sm1) it's as if there is a thin foam cover on the microphone that softens her delivery when compared to the stock ZS6. Likewise, when reviewing Van Halen's "Girl Gone Bad" the upper midrange leans more towards comfort as opposed to raw delivery.
If you will recall I mentioned that less than ten percent of the recordings in my personal music collection approach the "borderline" or push the envelope in the upper midrange and/or lower treble regions of the spectrum. When reviewing Pat Benatar's ode to the broken heart in "Promises In The Dark" I did appreciate the modified ZS6's presentation a little more though the resonance present at the 1:53 to 2:03 mark was exposed on both the stock ZS6 and ZS6(sm1) equally. The first sample is "Promises" remastered but I actually prefer the standard version. To my ears the remaster may sound more dynamic but it sounds more artificial. The standard version which is untouched may sound slightly congested in comparison but Pat's voice sounds more natural.
The modification doesn't necessarily mask the music; everything is just as present...... just a tad softer...... which you will appreciate on remastered recordings such as this.
In closing I'd say that the only minor drawback of the ZS6(sm1) is a minor loss of composure the busier the track gets (due to the slightly slower bass decay). To my ears the stock ZS6 deftly handles the entire frequency spectrum from top to bottom but those accolades are lost if you're treble-sensitive; your ears simply can't abide the energy present in the treble region. If you're pining after a ZS6 that you can tweak or refashion to mitigate said treble energy then perhaps your prayers have been answered with Slater's ZS6(sm1).
By the way, don't place an inordinate amount of weight on my "loss of composure the busier the track gets" remarks; the effect is very minor.
Yours truly is looking forward to Slater's ZS6(sm2) because it will likely be somewhere between the stock ZS6 and the ZS6(sm1). I am a micro-detail addict so more micro-detail is better in my book. My red, black and green ZS6's are all in stock form. The ZS6(sm2) will be my fourth ZS6 and a welcome varietal of my favorite in-ear monitor. Stay tuned for my feedback on the ZS6(sm2) in the near future.
Price: U$D ~45. Available in 3 colors, Red, Green, Black.
Upgrade cable: ~$9
The package is as simple it gets, with just 3 pairs of the KZ style eartips and the 0.75 2-pin detachable, everything inside a compact white box. Note: the provided eartips didn’t offer a good seal/fit, so most of the listening impression is based on using SpinFit and similar single flange eartips options.
The ZS6 follows the same shape and design as the previous ZS5 model, with the main difference of being made of metal (aluminum alloy) instead of plastic and adds some grills on the outer side of the shells. Needless to say that both ZS5 and ZS6 are following a Campfire Audio IEM design but with a more simple and plain finish. Like the ZS5 and many other KZ IEMs, the ZS6 also utilizes the 2-pin detachable cable feature; a less standard connectors of 0.75mm instead of the more common 0.78, but KZ already has an upgrade cable. The connection is quite good, much better than any standard MMCX option.
The ZS6 has a fixed over-ear wearing fit with a rather ‘polygonal’ look, that may a bit larger than the usual sub $50 IEMs and have potential fit issues for some people due the sharp ends. Isolation is around average and fit is a bit shallow because the short and straight nozzle.
The included cable is very average and carries some cable noise. It has a fixed memory wire and it’s terminated on a standard L-shaped plug and it reminds of the last Vsonic plug and y-split, with a slight rubbery coating.
Having listened to the ZS5 (v1) I was expecting a similar signature with some improvements overall on the newer ZS6. However, it was not the case. While technically the ZS6 is better in most of the sound areas over the ZS5, they noticeably differ in their presentation. If the ZS5 has a more standard v-shaped sound, with a warmer tonality and thicker mids, the ZS6 has much deeper V type of sound with a more pronounced bass and treble response, that while better in control it also makes the midrange more recessed and colder in tone.
The bass is quite powerful, rather linear through sub-bass to mid-bass, with a less lifted upper-bass. The depth is good with above average speed with the two dynamic setup. The quality and texture are quite good for the price, but it is missing on the fun factor that would be nice to have on these budget IEMs.
The midrange is the less favorable point on the ZS6 and biggest flaw. While it has the higher detail over any of the few KZ IEMs I tried, and also better than other similar priced options, it is missing in the whole presentation. Not only it sounds very distant but also has a very cold tonality and dry vocals. The ZS5 is richer and easier to listen (if you can tame the harsh treble down), and even the ES3 is much more enjoyable, sweeter in vocals more fun overall. Pairing the ZS6 with a warmer source is recommended.
The treble is elevated to match the amount of lows, and despite being so abundant it has the best control of the KZ other options, ES3 and ZS5. It has a same balance from low to upper treble as the bass, and it’s less sibilant too. Extension is decent and soundstage is around the average levels, if just trying to give a wider effect with the so v-shaped sound. For instance, paired with the Aune M1s, the ZS6 doesn’t have the so epic improvement in stage or imaging as the Fiio F3 or A&D D2 achieved.