Today at #TechWithAaron, I will be reviewing the KZ S2 True Wireless Earbuds.

KZ – Who?

Yes, the name of the brand is KZ Acoustics. If you haven’t heard of this brand, here’s a little breakdown: KZ Acoustics is a sub-brand of Linsoul Audio, and in recent years, KZ Acoustics has been making waves with it’s value-for-money earbuds. If you do a little research into the product offerings my KZ Acoustics, you’d realize that this brand creates many, many different wired earbuds.

While there are a few products launched by them that were a little hit-and-miss, Some of their models, like the KZ ZS10 Pro, have received really awesome reviews by other audiophiles, mostly for the stellar audio quality that you get from the earbuds, considering their (often) low price point.

My brother actually has a KZ ZS10 Pro – and Hearing it for myself – it’s not an exaggeration when I Say that that particular model from KZ Audio produces sound quality that is close to my Audio Technica IM-03’s (Which in it’s heyday, was priced at SGD $499 RRP when it first launched!). I will try to get a review done for the KZ ZS10 Pro at some point.

Now let’s get down to how I think the KZ Acoustic S2 (or KZ S2) Performs:

KZ S2 Review at a Glance:

While it has its quirks, the KZ S2 is so musical sounding that consumers on a budget should really consider buying these when shopping for their next bluetooth earphones.

What I Liked

  • Awesome audio quality: for just $40 SGD, will satisfy bass-heads, gym rats, as well as audiophiles that like strong bass emphasis but do not want to spend too much
  • Very Comfortable fit that is secure enough for workouts and daily usage
  • Great noise isolation with stock eartips

What I did not like

  • Touch controls and the strange mix of feature-set associated with these make for a slightly irritating experience 
  • Awkward USB port placement on charging case

How I got the KZ S2:

I bought this when I first stumbled on a indiegogo campaign for the KZ S2 in March – And was one of the first 100 to buy the KZ S2 from their indiegogo page.

Early adopters like me (which have no idea how good the final product would be – other than deriving from their marketing materials on the indiegogo page), but I did get the earphones at $29 USD (or about $40 SGD), which is really, really cheap for a Bluetooth earphones, especially one with this much features (more on that just below).

The KZ S2 is KZ Audio’s third bluetooth earphone release (Prior models was a KZ S1 and KZ S1D), So when I bought this, I was hoping that KZ Audio would have taken some notes about the weak points in their previous models, and create an even better product.

What are the features on the KZ S2?

For that, we can turn to their product page on indiegogo. The KZ S2 really sounds impressive on paper. In Summary, it has:

  • Bluetooth 5.0 (!) via Realtek 8763 Chipset, with up to 15m Coverage
  • Hybrid Driver Setup: A 7mm “Double magnetic” Dynamic Driver + 1 Balanced Armature Driver (!!) with frequency response of 10Hz to 20kHz
  • AAC Codec Support (Great, but perhaps not the best – more on that later)
  • “High Performance Mode” to reduce lag between audio/video
  • CVC Noise isolating microphone (both sides
  • IPX5 Splashproof rating (So this can be used for workout sessions!)
  • TRUE TWS (Meaning you can pair either right, left, or both simultaneously to your device (!!!)
  • Touch Controls
  • 40ma TWS Battery and 500ma battery in Charging Case, giving 2 hours of talk time (or 4 hours of music listening time) from the TWS itself, plus an additional 14 Hours of listening time and 10 hours of talk time when the earphone is re-charged in it’s charging case
  • USB-C port Charging case (Finally…)

Such features (particularly true TWS and Hybrid-Driver setups) are uncommon on $99 Bluetooth Earphones, let alone just $40SGD. Even at it’s current selling price of US$35 on their crowdfunding page, I think we can all agree that based on the specs alone – this is almost unheard off in it’s price range.

Yet, here we are. So, my review will focus on: Does it really deliver up to its promises? Let’s delve in

Unboxing of the KZ S2:

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The KZ S2 came packaged in a basic looking white box. Not surprising for a budget earphone. 

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The included accessories are a little sparse – but functional. We get an English manual (Count me surprised!), A USB Cable, The Charging Case with the earbuds inside (metal contacts of the earbuds were protected by plastic to prevent “full” charging of earbuds en-route), and a pair of small and large spare silicon eartips (the medium size silicon tips are already pre-installed on the earbuds). Overall, the accessories are what you’d expect to receive from a quality earbud and they are enough to get you going.

I bought the foam eartips recommended by KZ Acoustics on their indiegogo crowdfunding page as well – (A $5 USD add-on), but did not use it for the review (partly to keep this review fair…and also because I never felt the need to use it in this review. More on that under “Noise Isolation”.)

While the indiegogo page only lists the earphones as available in black and white, it looks like their are grey and red colour options coming up in future – KZ Hints at this via the colour option marks on their packaging20200521_205850 (Large)

Carrying Case: 6.8/10

Functional, but a few cost-cutting measures were clearly made here.

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First off: Let’s examine the charging case. The charging case is matte black, but there is a matte white version as well, with the front containing the KZAcoustics Logo. The flap opens up from the top – this kind of reminds me of the Apple Airpods.  

KZ S2 Case Bottom
The case of the KZ S2 does it’s job – but the strange placement of the USB Charging port could be part of a cost cutting measure. But for it’s price – I think that’s forgivable

The case does the job, but it’s pretty obvious some cost cutting has occurred here. Most notably, the USB Charging port is USB-C (great!) but located at the bottom of the case – a really weird design choice (see above photo). Also, the charging case itself does not detect if the flap is open or closed: so if you wanted to know the battery life of the earbuds, you need to press the button located at the back of the carrying case.

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The case can’t detect if the flap is open or closed – So to check the battery life left in the charging case, you have to open the case (to see the indicator LED), and then press the button located in the middle of the back of this case to check the battery life.

With that said, the carry case does it’s job well enough, with just enough magnetic force to “snap” the earbuds into the pogo pins, charging the earbuds when not in use. Just don’t intentionally open the earbuds, flip the carrying case upside down and shake the earbuds to see if it would fall out – because they would definitely fall out (yes…I just tried that one out while writing this…😂). The bluetooth earbuds would turn on automatically when you take them out of it’s charging place – so core functionality is still great.

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The touch sensitive controls are the matte portions of the earbuds, which makes it easy to differentiate where to press when the earbuds are in your ears.

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The side of the housing shows “Dynamic x1, Balanced Armature x1” to remind you of the driver tech inside this earbud, as well as the orientation of the earbud (left/right).

The earbuds are charged by the charging case via 3 pogo pins (and the accompanying pads on each earbud)

Comfort and Noise Isolation: 9/10

The ergonomics of the KZ S2 is really well done.

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The KZ S2 earbuds – with the blue protective plastic on top of the 3 pogo pin pads meant for charging.

The Earbuds themselves are fantastic. The earbud shell is made of glossy black plastic – which does mean it is a fingerprint magnet – but the overall build quality felt solid enough. The shape of the earbud is excellent – earbuds fit snugly in my ears, and never felt uncomfortable in my ears even after extended sessions. There is a wing that slightly protrudes from the top – which contours to the top part of the ear, making the fit feel a little better in my ears.

The silicone tips that come with the earbuds are also just right in terms of pliability, with a long-enough flange to provide a great seal around my ears without ever feeling finicky. In fact, I bought extra foam eartips (recommended by KZ) to accompany this pair of earphones, but didn’t feel the need to use those – that’s how good I felt the stock silicon eartips were.

The earbuds don’t come out of the ear easily thanks to the well sized ear-tips. Unfortunately it’s Circuit Breaker/Lockdown in Singapore so I didn’t get to test if the earbuds would fall out of your ears when running, but these earbuds have worked well for indoor gym and static sessions.

Connection and Wireless Stability: 8.5/10

This Earbuds uses a Realtek 8763 Bluetooth 5.0 True-TWS bluetooth chip – and I have to say it is one of the better Bluetooth earbuds when it comes to connection stability.

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After pairing it once to my smartphone, The KZ S2 always remembered to “re-pair” to my phone as long as it was in range.

Indoors, audio does not cut out unless I am far (beyond 8m) from my signal source. Outdoors, there was significantly less music drop out’s compared to other budget earphones I’ve used, including the Edifier TWS1 and Creative Outlier Gold. Even when crossing the road, I encountered few drop-outs when both earpices were used. However, there can sometimes be a slight pitch shift (of about 4-10hz higher or lower) if passing crowded areas, although this strange issue usually resolves itself after a couple of seconds.

The earphones allows you to use it in mono or stereo – and you can connect just a single left or right side. Nifty – usually Bluetooth earphones of this price range do not feature true TWS Pairing like this one.Screenshot_20200613-230829_Settings

If it matters, when connected to the phone, both sides of the TWS earbuds connect to the phone under a single Bluetooth name – Which is neat, compared to older-standard bluetooth earphones that sometimes end up requiring two different pairings and listings on the phone to give “true-TWS” pairing.

On board Controls: 6/10

The KZ S2 uses Touch Sensitive points (Yes!). Sadly the feature set tied to these buttons are underwhelming and slightly annoying.

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This is the second TWS earbuds I am using with touch-sensitive control. I’m a fan of touch sensitive earbuds as it usually feels modern, however this earbud highlights why someone might not want touch sensitive earphones. The controls you can mess with on the KZ S2 seems pretty good at first: Single tap to pause, Double tap either the left or right earbuds to skip to the previous (or next) track. However, there are two glaring issues I have faced:

  • First, A really annoying feature: If you press and hold any of the earbud touch – sensitive areas for more than 6 seconds, both sides of the earbuds will be turn off. This is really annoying as I sometimes would listen in stereo, and remove one side of the earbuds to talk to someone for a short while and listen to the conversation. Too often I would accidentally turn off both sides of the KZ S2 by accident when doing this, as I accidentally touched the touch sensitive side with my palm for too long. To re-start the earbuds, one must press and hold the touch-sensitive pads of both the left and right sides for 6 seconds. So yes, pretty annoying…this has happened to me a few times in a week 😂
  • No Volume control via the earbud. I would rather have had this feature set rather than a feature to turn off the earbuds so easily by mistake.

There is also a short time lag (of about 1 second from time of pressing to action being taken by the smartphone.

There is a high performance mode if you tap the earbuds 3 times rapidly. This reduces time lag a little more, however it will negatively impact the battery life of the earbuds a little more. 

Sound Quality: 9/10

The KZ Acoustics S2 is definitely one of the most musical sounding true wireless Blutooth earbuds you could buy for less than $50.

Out of the box, the earbuds sounded extremely boomy, very v-shaped (very recessed mids), with somewhat shrill highs. However, I gave time for the earbuds to “break-in” for about 2 weeks.

It could just be simply my ears adapting – but it seemed like the initially shrill highs tamed down, and the mids came through a little more. It’s still a v-shaped sound signature, but can be tamed to my liking with an EQ.

Bass is strong and pounding, especially in EDM tracks – purists might want to avoid this as some might find the bass a little overwhelming (even though I love extra oomph in the bass!). Vocals sounded natural enough despite the slightly recessed mids. Highs came through clear enough – it can sometimes still come off as slightly shrill, but this is easily tamed with an EQ.

Soundstage was pretty good with the KZ S2. When Playing “Don’t let me down” by Chainsmokers (Illenium remix) – in the beginning part of the song, you can hear the stereo delays of the vocalist really well – especially considering the value you get from this earphones. Amazing for $50 – at this price point, most other earphones which have strong bass usually lack high end presence. The Balanced armature driver that accompanies the dynamic driver really helps the KZ S2 sound like no other in it’s price point.  

The following is the EQ that I usually use with KZ S2 – To get “neutral” mids, and slightly tamed highs. I sometimes boost the 63hz a little further when working out – Bass really gets me moving a little more! For normal listening, no adjustment or -1db on 63hz works well for me.

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Battery life: 7.5/10

Unfortunately the battery life on these are a little short – coming in at 4 hours on a single charge for music playback, and 2 hours for talk time. I got about 3 hours 40 minutes of music playback so it’s quite close.

While this earphones is great and more than enough for daily commutes and work, those intending to use this for long conference call sessions might want to take note of the shorter battery life.

Part of the reason for this short battery life is the use of the AAC Codec – While touted as “the best option” for music playback by KZ Acoustics, this comes at a premium of battery life as AAC is much less power efficient than Apt-X. Just something to take note.

Mic Quality: Slightly Below Average

While the Mic is supposed to be “CVC Noise cancelling”, it does not seem to help the KZ S2 bring out better mic quality. There was still a fair bit of ambient noise, and my voice didn’t come out as clear as I’d hope it to be. I guess some corners were cut to make great audio possible at a low price point, and the mic component was one of those features to get the cut.

Conclusion (Overall Impressions) of the KZ S2 – 9/10

20200521_204729 (Large)Overall, for those on a budget, the KZ Acoustics S2 is probably one of the best earphones you could get for less than $50, and I would happily recommend these to any consumer looking for a true wireless bluetooth earphone and is on a budget.

Yes, it does have its quirks: From a strange choice of USB port placement, irritating touch-controls and below average mic quality, but for EDM lovers and people that love impactful bass with their music, it does so well at its core function – music playback, that I am willing to overlook the little quirks and make this my most recommended product for those on a budget, be it for gym sessions or using it on the go while commuting to work or school.