Intro (important)
Before you continue reading, you can and should read my ‘about author’ page on head-fi to get a taste of my sound preference and test tracks. I bought these for $42 AUD ($30 USD) on sale at Gearbest. I bought these after reading all the raving reviews, even some comparing it to the Sennheiser hd600 but I guess they were all hype.

Listening and tests were mainly done with my Xiaomi 4X phone using Spotify's extreme quality (320Kbps, 24bit, 48Khz?). Note, my Xiaomi 4x output is slightly warm sounding and bassy (a solid 3-5dB more bass) compared to audio from my Ipod 5th gen and my computer (I5 core). The 4X output also sounds noticeably clearer and has better imaging than both my ipod and computer.
I usually listen at a low to very low volume. When using my Xiaomi 4X I listen at 20% of max volume (3 notches). Thus why I prefer a slight L or V shaped sound signature as bass output decreases with lower volumes. This also means my evaluation of the bass might not be as accurate.



Sound

I have listened to these headphones for roughly 24 hours accumulated over a month. I initially burned them in for half a day. The headphone still sounds the same, maybe just a very slight decrease in treble. Volume is quite soft, I need to turn my Xiaomi 4X volume up to around 30-40% to be as loud as my Sony MDR-ZX600 at 20%.



- Treble is way to Hot, particularly the highs. This could be attributed to the multiple relatively large peaks which are present at around 2k, 6k, 10k, and 15k (thanks to Rtings.com frequency chart). The biggest peaks are present at 10k and 15k. As a result the headphone sounds very unnatural and harsh. I would not consider myself a treble sensitive person but the super boosted highs just make it sound so unnatural. Like Tyll from Innerfidelity said, I have to admit these do sound pretty decent IF you EQ everything from around 1.5kHz gradually down to 5dB or even more.

I see some people being shot down (even comments being hidden What?!!) for saying the highs are too hot as though there’s some kind of cult following thanks to the headphones hype. Believe the hype if you want but just take a moment to think about it. Tyll from Innerfidelity is at his retirement age meaning his ability to hear highs is hampered, yet he says the highs are way to hot, like “razor blades”. Doesn’t that ring any bells? Maybe at very high volumes the bass might come out more thus balancing out the treble but even then I did not find the bass to be strong enough to mask the treble. Regardless, you shouldn’t be listening at high volumes, unless you enjoy accelerating your hearing loss.

Anyways, below is my EQ setting. Even with my EQ setting treble may still be hot for some. I’ve also attached a picture of a frequency curve versus age graph for those who do not know about age-related hearing loss (Presbycusis).






Otherwise like I said, these will sound very unnatural and extremely harsh. Although mids are already quite forward, I experimented with removing the foam screen in front of the driver to further boost the mids. Mids did become even more forward but it also lifted the already super elevated highs. I have even swapped the stock pads with Velour pads which only reduced the isolation. Thus the bass was reduced which brought forth the hot highs even more.


- Mids are a bit forward but nowhere near as much as the highs. I find it okay, some may say it is a bit recessed which could be attributed to the relatively more prominent sub-bass and super elevated highs.Personally i did prefer a little more of the mids hence why i experimented with taking out the dampening foam positioned in front of the driver.


- Bass is okay or a little bad with stock pads and very bad with Velour pads. With stock pads (plastic pads) I have to say bass gave more than what I first expected given that it is a semi-open back design. Sub bass is quite decent, nearing the amount that my Sony MDR-ZX600 puts out though doesn’t go as deep. Mid-bass is tight and has good quality but is a bit soft especially when compared to the mdr-zx600. Overall, I’d say bass is quite coherent and neutral besides the elevated sub-bass.

With Velour pads, bass was pretty much non-existent as the velour pad could not create a seal since it is made of fabric. As I said before, this brought forth the mids and already elevated highs even more.



Soundstage and imaging

I hear quite a few people say that these have a very wide sound stage but I do not think so. There is a difference between having a big soundstage and sounding diffused. I don’t know if it’s because the bad implementation of the semi-open design and/or the bad tuning but the 668 sounds quite diffused like listening to a concert from 100+ metres away. Good soundstage should sound like being surrounded by musicians a few metres away. If you want to know what very good soundstage and imaging is like then try the Sony mdr1A, you will tell from comparing that the 668B is diffused. Imaging on the 668B is pretty much on par with my mdr-zx600 if not a little worse due to the diffused soundstage.

Isolation

Pretty much non-existent due to the semi-open back design.

Design and comfort

It is mainly made of cheap feeling plastic with visible joint gaps. The headband consists of a rigid metal wire structure and has two probes with pads that rest against the top of your head. The plastic pads made me sweat quite a bit and was uncomfortable since the two small head pads could not distribute the weight of the headphone sufficiently. As expected from a semi-open headphone, there are holes at the back of the housing which act as vents. The worst thing about the 668B was the stock pads which I just could not describe as pleather but rather as plastic. The plastic pad was very rigid and made my ears sweat quite a lot. It was so uncomfortable that I had to make a permanent switch to velour pads even though that meant near non-existent bass. Apart from all the negatives, I must commend Superlux for implementing detachable cables on such a cheap headphone and providing a 3m cable.
Below is a picture of the headphone with velour pads on.





Summary

The 668B is just not worth it. You could have better headphones for roughly the same amount of money (such as the Sony mdr-zx600) or even better to invest in a slightly more expensive headphones under $100, that way you don’t need to think about upgrading for a while. There is no excuse for EQ, any headphone put through a good EQ software can sound decent. It’s like strapping a jet engine on a Toyota Prius, of course it would out speed a Ferrari, but will it perform and drive as coherently? No. Plus I do not want to waste time switching my EQ pre-set every time I want to listen to the 668.

I could only recommend the 668B to the elderly or anyone else who has hearing loss. Or for anyone who is on an extremely tight budget, want a neutral sound, does not mind spending time switching EQ pre-sets, and are willing to spend extra on better ear pads. Even then you’d still have its diffused soundstage and near non-existent isolation.

DISCLAIMER: I am not affiliated with any companies. I will try to be as objective as a i can in my reviews.



Specifications:
Driver: 40mm dynamic driver, PET diaphragm, Neodymium magnet
Impedance: 40 ohm
Cord length: 1.2m
Weight: 170g
Frequency: 6 Hz - 25 kHz
Sensitivity: 104 DB
Type: Closed back, On ear (Not Circumaural)

Intro (important)
Before you continue reading, you can and should read my ‘about author’ page on head-fi to get a taste of my sound preference. You’ll also find the test tracks there. I bought these a few years ago for $50 AUD on sale (usually cost $110 AUD). These sound the same as the ones without the play/pause button, I had both but gave away the one without the button to my family. The one without the button was my first pair I bought around 6 or 7 years ago. They sounded so good that I bought another one when it went for sale again 1-2 years later (I think due to discontinuation in Australia), this time it had a play/pause button.

Listening and tests were mainly done with my Xiaomi 4X phone using Spotify's extreme quality (320Kbps, 24bit, 48Khz?). Note, my Xiaomi 4x output is slightly warm sounding and bassy (a solid 3-5db more bass) compared to audio from my Ipod 5th gen and my computer (I5 core). The 4X output also sounds noticeably clearer and has better imaging than both my ipod and computer.
I usually listen at a low to very low volume. When using my Xiaomi 4X I listen at 20% of max volume (3 notches). Thus why I prefer a slight L or V shaped sound signature as bass output decreases with lower volumes. This also means my evaluation of the bass might not be as accurate.



Sound:

Overall the headphone has a ‘V’ shaped or ‘L’ shaped sound signature with elevated bass and slightly elevated highs. Hence it could be considered as a warm sounding. Throughout the review I may refer to the headphone as the ‘600.’

You can get my impressions on sound mostly from reading the following rebuttals regarding a 2 star Headfi review which claims:

1. They sound muffled: No they do not sound muffled, especially not as bad as you described it sounding like ‘music through a woolen balaclava.’ The reviewer also states he wears glasses hence compromising the seal and thus sound quality. I even tested the headphone while wearing sunglasses and found that there was very minute change in sound, in fact all it did was compromise a bit of the seal hence dialling down the bass a little, thus mids + highs could be more in focus. Mids are a bit recessed when compared to the relatively more forward bass and highs but I would not call them muffled at all. In fact vocals have noticeably more presence and detail compared to Sony’s flagship portable headphone, the mdr1A which cost $300 AUD. I have also listened to a bunch of other headphones such as the Grado sr80, Bose QC’s, ATH M50X, Meze 99 classic, and can confirm the mids and highs on the 600 are fine. Another reviewer even said they did not notice the recessed mids until they read the 2 star review and really concentrated on the mids.

(UPDATE: i have edited the paragraph below after listening to the Koss Porta Pro. Apologies for previously assuming it was bass light as i thought it would be just like the Grado which have nearly no sub-bass.)

The reviewer also states their previous headphone was the Koss Porta Pro which has an even stronger L shaped signature with strong bass and very smoothed off mids/highs thus sounds even more 'muffled'. So i don't know how they're complaining about the 600 sounding muffled. I was actually really surprised at the large amount of bass the Koss was able to put out given it has an open back on ear design which usually means no bass. I do not understand people who rave about open backs, esp. ones with minimal foam pad and no seal like the Grado's. How can you rave about a headphone that has near non-existent bass, especially sub bass? People complain when mids and highs sound slightly recessed but when it comes to the full bass spectrum being near non-existent no one bats an eye, and even praise it.

Highs on the 600 sound detailed, clear and natural. High hats, cymbals and acoustic instruments sound crisp thanks to the slightly elevated highs. Though I would say highs are not as crisp and detailed as my Xiaomi ANC iem’s which have that edge thanks to the 2 BA’s. Cymbals on the 600 are a little splashy when compared to the Xiaomi ANC’s. Though some people might say the highs on the Xiaomi ANC’s are too bright so the slightly dialled down highs of the 600 could be a good thing.



2. Bass is too strong and drown out other frequencies: I am not a basshead but rather a bass lover i.e. I appreciate slightly elevated bass but without the sacrifice of mids and highs. The ATH M50X bass is even more elevated and boomy than the 600’s. I found the M50X bass to be too boomy and excessive. I would consider a basshead headphone to be one of the old Monster headphones or the Sony extra bass series which both have more bass than the 600. Sub bass on the 600 extend deep and mid-bass has a very nice punch. There is very little bass bleeding into the mids if not none at all. Maybe if you are a very high volume listener then you might experience some bass overwhelming but then again you shouldn’t be listening so loud unless you enjoy the sound of ringing…. ringing all the time, AKA tinnitus. The bass quantity on the 600 is perfect to me.



3. Pressure of the headband and unfriendly for glass wearers: If you wear glasses you will find any headphone uncomfortable unless there is no clamping force meaning it will fall off your head. I have even tested wearing the 600 with sunglasses on, I found no issue with glasses being in the way as the highest point of the earpad is just above my ear hence I just rested the frame ontop of the earpad. Only when I put on my sunglass and headphone on without care did I get a slight compromise in seal. I suggest glass wearers to get good earphones since even over ear headphones would be worse as It would have a compromised earpad seal since the glass is in the way. Sound will change without a complete seal. I find the headband clamp force is perfect on the 600. The mdr1A’s clamping force was too light for me as it would move from my optimal seal position easily. I understand that some people are also not fond of on ear headphones as they place direct pressure on the ear. It’s just a matter of preference, personally I like on ear headphones as over the years i have gotten used to the 600, plus I find over ears too heavy.


Soundstage and imaging:

Soundstage is ok. I have not directly compared it with other over ear headphones but it is nowhere near as good as the mdr1A’s amazing soundstage. From my memory of listening to other on ears, I’d say the 600’s sound stage is on par with other on ear headphones. Left/right separation is good, width is ok, but depth and height is quite bad when compared to the mdr1A which has an advantage thanks to the over ear design.



Isolation

Isolation is very good thanks to the great earpad seal. At my low listening volume I can barely hear any ambient noise including people chatting.



Design and build

The first 600 I bought 6-7 years ago is still working today although around 1.5 years ago the pleather pads outer plastic coat started to peel off. Underneath the plastic coat is not foam but another layer which holds the foam together underneath. It’s a soft velour like material so basically you get a free velour pad upgrade after 6 years ;D, thanks Sony. The headbands plastic coat which holds the foam together has also started to flake away. Sound wise it is only altered very slightly only because of the plastic pad coat coming off which helped keep an airtight seal. With new pads I am certain it would sound the same as when first bought. I’m surprised my first 600’s still work as I bashed them around quite a lot and used it pretty much daily. The extra protective cable sheath layer at the jack has also came off. Apart from that, everything else is in perfect working order.

As you can already tell through my many years of using and abusing the 600, its build is very good. The back of the drivers’ housing is made of metal while the rest of the headphone is made of plastic. Like most other headphones, the earpad is made of pleather which makes my ears sweat a little. The foam used in the earpad is not as soft as the amazingly cushy mdr1A which cost 6 times more at $300 AUD. There is also a decent amount of padding on the headband. The 600’s flat rubber cable is very nice. After 6-7 years of near daily use I expected it to degrade but it is still in mint condition. The cable also has an extra protective sheath at the L shaped jack to reduce stress. There are protruding rubber sheaths which come out of the housing where the cable attaches to reduce cable stress. The new 600 has a play/pause button built into the cable on the left. I notice some headphones with play/pause buttons situated on one side of the cable suffer channel imbalances, but I did not notice any with the 600.

My only problem with its build is the cable from the splitter to the housing is too long. As a result, when I’m sat down at a desk, the splitter sometimes gets caught by the tables edge when standing up.



Summary

Overall, I would highly recommend the 600. The 600 ticks all my boxes. It has an elevated bass but not basshead level and with little to no bleeding. Mids and highs are detailed, plus build and isolation is great. The only thing I could fault is that when comparing with the Xiaomi ANC’s, the 600’s highs could be a little more detailed and crisp. I would say these have very good value. I highly doubt you could get a better sounding headphone that is less than or equal to $50 AUD. The 600 could probably even compete well with headphones under $150AUD. Personally the 600 beats the M50X due to its bloated bass and also beats the Grado sr80 due to its near non-existent sub-bass plus hot highs. For anyone thinking of getting the Sony mdr1A, don’t! Get these instead as they sound more detailed for 1/6th of the price, unless you really love soundstage which the 1A excels at.

There is a newer version called the MDR-ZX660AP which seems to have a better build and according to others sounds exactly the same, if not slightly better.

DISCLAIMER: I am not affiliated with any companies. I will try to be as objective as a i can in the reviews.


Before you continue reading, you can and should read my ‘about author’ page on head-fi to get a taste of my sound preference. You’ll also find the test tracks there. I bought these for $100 AUD from someone who owned it for 1 year.

Listening and tests were mainly done with my Xiaomi 4X phone using Spotify's extreme quality (320Kbps, 24bit, 48Khz?). Note, my Xiaomi 4x output is slightly warm sounding and bassy (a solid 3-5db more bass) compared to audio from my Ipod 5th gen and my computer (I5 core). The 4X output also sounds noticeably clearer and has better imaging than both my ipod and computer.
I usually listen at a low to very low volume. When using my Xiaomi 4X i listen at 20% of max volume (3 notches). Thus why i prefer a slight L or V shaped sound signature as bass output decreases with lower volumes. This also means my evaluation of the bass might not be as accurate.



Sound
Sound test is based on the cable without the control button as the cable with button sounds awful. I will talk more about the button cable later. I will be mostly comparing the 1A to the Sony mdr-zx600. Throughout this review I may refer to the mdr1A as the '1A' and the mdr-zx600 as the '600'.
Overall the 1A has a 'V' shaped sound with elevated bass and slightly elevated highs. It could be considered as a warm sounding headphone.

- Slightly softer (one notch on Xiaomi 4x) than mdr600 even though 1A impedence is less.

- A bit less clarity and more muddled than mdr600. Especially with high hats and cymbals which sound unnatural and a bit splashy when compared to the 600. Snare drums also sound low quality like it has been downgraded from 320 to 128kbps. I suspect the 1A’s unnatural sound could be attributed to the massive peak at around 9khz and a big drop off from around 12khz onwards (thanks to rtings.com frequency graph).

- Around same bass as mdr600 though 600 may have a tiny bit more boom due to on ear design which position driver closer to ear and seals better. Quality wise both are same, no bleeding or overwhelming of other frequencies. The bass is very nice on both headphones, i'm a big fan of Sony's bass.

- Vocals don’t have as much presence as 600. Too smoothed off for my likings. As a result, less detail and clarity. This vocal recession is evident when looking at the frequency graph which shows a dip in mids with the lowest amplitude at the low-mids.

- Guitars and pianos do sound more realistic on 1A and has very pleasing natural tone. Very weird considering it has more laid back mids and highs than mdr600. Maybe due to its better soundstage it sounds more realistic as most classical/acoustic sound best with wide soundstage, as though you’re in a concert hall. Or it could be a result of the 9khz peak.



Soundstage and imaging

- This is where the headphones really shine. Soundstage, imaging is excellent especially left/right separation when compared with 600 which barely has any. Depth is also great, but height is just ok. The 600 is on ear while 1A over ear so 600’s lack of imaging is understandable. Excellent soundstage may be attributed to the long vent slit at the top of the housing.

Isolation

- Even though 1A is closed back, Isolation is quite bad and very similar to how open backs would perform. This is probably due to the large vent slit at the top of the housing



Design, build, and comfort

- Look very premium, classy and luxurious.

- Build is very nice. Mostly plastic but very sturdy and durable looking and well finished. Adjustment band is metal and has nice precise clicking response when adjusting. Pads are pleather which made me sweat a little but the foam is very soft, plush feeling, and thick. Pads fit my ears nicely though note that I have relatively small ears. Headband top is also nicely padded; same pleather material as pads except might be a little thicker. Cable look and feel very nice and I would say relatively thick compared to conventional ones. End connecting to housing is very sturdy and connects firmly. Also has cable with single button for play/pause but sound quality deteriorates a lot with this cable, everything becomes muddled, sounds like downgrading from 320 to 128kbps. Would take the mdr600 over 1A with button cable any day. The mdr600 was so good that once it was on sale again I bought another one for backup, this time it had a mic/play/pause button in the cable. Comparing my original mdr600 with the backup one which had play/pause button in it, they sounded the same. For the mdr1A which cost 3 times more than the mdr600, it was highly disappointing that sound quality deteriorated with the cable that had play/pause button.



Summary

- Overall, I think the mdr1A is just a mdr600 driver placed in a over ear headphone housing as both have the same Sony sound signature. Mdr600 driver in the housing might even sound a little better. Maybe the aluminium coat on the 1A's driver is actually just a marketing gimp and is holding the sound back, who knows. Considering it is around 3 times the price of the mdr600’s, sonically it is just not worth it and as a result I would not recommend these headphones. Even though it may be very comfortable and soundstage/imaging is excellent, the detail and clarity is subpar to the mdr600 and for something that cost 3 times more this is unacceptable. Its lack of isolation is also a big letdown considering these were marketed as ‘portable’ headphones.



Comparing the headphones to speakers, I would much prefer a good set of speakers (mdr600) in front of me rather than a surround sound system (mdr1A) that has speakers which sound less clear. I got my mdr600 for $50 AUD (a few years ago when AUD was approximately equal to USD) which is half price off RRP ($100 AUD). On the other hand, the mdr1A rarely has sales in Australia, is very rare to find in stores, and is usually $300 AUD. I expect a lot more for something that cost 6 times more than what I paid for the mdr600. Personally, I would not pay more than $150 AUD for these considering the mdr600 have better clarity and detail for just $50AUD. As a result of the lacking clarity and detail, I have sold the mdr1A after one month of listening. Perhaps if I did not have the 600’s already I would’ve kept it but since I do and I’m so accustomed to its fit, I could not justify keeping the mdr1A. Maybe the mdr600 is just performing way above its price point.



All in all I’m a bit on the fence with this can. The bass, soundstage/imaging, build, and comfort is exceptional but the mids, highs, clarity, and isolation is very disappointing considering the price. Personally, the biggest deal breaker is the mids, highs and clarity as I firmly believe that as headphone price increases, the clarity and detail should also increase which is not the case here. Surely there must be other headphones at this price range or lower which can offer all the goods of the mdr1A without all its cons. Then again, every headphone at this price range is unique and must have some compromises so where one lacks in a certain aspect, another is better at it. Maybe the rival ATH MSR7’s would be the ones for me but from reviews I see they are bass light and uncomfortable. I guess it’s all about compromise so choose the one that pleases you most.

Disclaimer: All my reviews are based on my own opinion and are not and will never be corporately biased, even if companies sent me products (someday this dream will come true i hope haha).

Note: This is a review of the 3.5mm jack version and NOT the USB C version which is built differently by another company (affiliated with Xiaomi), and apparently sounds bad according to OTHER reviews.
I bought this iem with my own money, no company affiliated discounts.
As with my other reviews, i will constantly update the review. If you want my final most precise opinion on the product, please come back after a month or few months. Sorry for this as I am new to the game so my opinion may change as i become exposed to more better products.

Specs:
- Drivers (per side): 2 Balanced armatures + 2 Dynamic drivers??

- Frequency range: 20Hz - 40kHz. ‘Hi-Res’ certified
- Active noise cancelling
- Battery life: 12 hrs
- Cost: $42USD

Packaging:
Nothing fancy, rather minimalist but does the main job of protecting the iem as it is encased in clear plastic. Packaging is the same as Xiaomi's other iem's. Personally, I like the minimalist look.



Accessories:
Other than the tip already on the iem (a medium tip), there are 3 other tips (XS, S, L). All tips are silicon and have this oval shape which I have never seen before but fits nicely as I will describe later. A bag for storing the iem is also included. It's a nice feeling suede bag but is just too small to safely and quickly store the iem, you'd need to fold/coil the iem quite nicely to be able to fit it in the bag. Alternatively, you could get a KZ earphone hardcase for around $2 which would be worthier for an iem this nice to be stored in. The grey plastic mould that the iem is originally wrapped to which by the way has a very premium feeling silicone coat over it could technically be used as a storage for the iem but would be quite a hassle as you'd need to carefully wrap the cord around the mould every time.

Design and Build:
The iem is built very well. The drivers housing is made predominantly of perfectly machined metal which gives it a weighty premium feel. I see quite a few people complain about metal housing in other iem's since they don't like the cold feel but i honestly find it cool and refreshing when initially inserting the iem, it does warm up to body temp after a few seconds anyways. After all, metal housing = durability. Plastic is used for the front part which attaches to the nozzle, a nice touch for those who dislike the cold metal feel. Looking from the bottom of the housing, there is a long vent slit. Despite this the isolation in passive mode is still decent, I’d say average or just below average. The nozzle itself is oval shaped which I assume is where the 2 BA’s are placed and stacked on top of one another.





The cable is fabric braided from the jack to the volume/play/pause unit and from then on its a silicone cable. I assume silicone was chosen to reduce cable noise (microphonics) while the rest was fabric braided to eliminate tangling. The Jack is gold plated and is attached to a nicely machined metal L shaped plug. The tag you see in the picture below has a QR code on the back which you can scan to verify that it's an authentic Xiaomi product.



The unit which houses the ANC circuit and the play/pause/volume buttons is also made of nicely machined metal and has a spring assisted clip on the back to attach to your collar or shirt pocket as the unit is a bit too weighty to hang free. There is a switch on the side of the unit where you can control 2 levels of ANC. Although I don't find any use for the intermediate level ANC function it is a very nice addition which i don't think you can find on any other ANC phones. Hats off to Xiaomi for their ability to somehow place the ANC circuit and a battery which last 12 hours into the volume/play/pause unit. All other ANC iem’s I’ve seen and even some ANC headphones have a bulky ANC circuit and battery unit located on the cord near the jack which is very inconvenient. Even Bose’s QC20 iem which cost 7 times more have this bulky design. There is also a small green light which turns on when ANC is on. It flashes red when power is low. You can use the ANC while charging its battery.



The only things i can fault is the cover of the charging port which is very hard if not impossible to open unless you have very long nails. I would have also liked the charging port to be USB C or Lightning or even better, a magnetic charge port (like the mac books). I find Micro USB very flimsy and for something this small, constant plugging and unplugging can increase the risk of damage and failure. Nevertheless, you can buy a cheap magnetic charger adapter for micro USB to overcome this like I did. Another flaw is the cable from the volume unit to the drivers housing is too long when the unit is clipped to the collar making the cable puff out which can look a bit funny? This does eliminate the cable rubbing against your shirt thus reduces cable noise (microphonics) so I’m pretty cool with that. In a way it also supports the weight of the driver + housing. On the other hand, the cable length is perfect when the unit is clipped to my shirts pocket. Did Xiaomi just assume we all wear shirts with pockets or am I just behind on fashion???

Comfort and fit:
Personally, I find these earphones very comfortable. The slightly angled nozzle prevents the housing from touching the auricle (outer ear) though I find all other non 'over the ear hooked' iems which doesn't have an angled nozzle fits perfectly anyways. I have relatively small ears so i personally find all 'over the ear hooked' iems uncomfortable as the housing sits 'inside' or against the auricle. Thankfully the Xiaomi is not an over ear iem.

The oval ear tips fit very well. Initially it felt a bit weird but after a while it felt comfortable. I have tested them on my Remax S1 Pro iem's which does not have any vents and concluded that i was able to get a complete seal with the ear tips as the driver was not able to produce any sound when i deeply inserted the ear tips.





Sound:
NOTE: this has been updated

IMPORTANT: Before you continue reading, you can read my ‘about author’ page on head-fi to get a taste of my sound preference. You’ll also find the test tracks there. I have owned these for over a month now and have probably amassed at least 100+ hours listening to it. I initially burned them in for a day. Listening and tests were mainly done with my Xiaomi 4X phone using Spotify's extreme quality (320Kbps, 24bit, 48Khz?). Note, my Xiaomi 4x output is slightly warm sounding and bassy (a solid 3-5db more bass) compared to audio from my Ipod 5th gen and my computer (I5 core). The 4X output also sounds noticeably clearer and has better imaging than both my ipod and computer.
I usually listen at a low to very low volume. When using my Xiaomi 4X i listen at 20% of max volume (3 notches). Thus why i prefer a slight L or V shaped sound signature as bass output decreases with lower volumes. This also means my evaluation of the bass might not be as accurate hence why i find the bass (especially mid-bass) a little soft.

According to TechManZ (a YouTube tech reviewer) these sound exactly like the Xiaomi Pro HD's? I cannot confirm that since i haven't heard the Pro HD's but I have to say that the Xiaomi ANC sound very nice. Looking at the frequency graph (thanks to 'The Phonograph'), it seems that the Pro HD's overall bass is softer and more mid-bass oriented than the ANC's. I’ve always had that preconceived notion that earphones would never sound as good as headphones, even when comparing a $100 iem to a decent $50 headphone due to iem’s small drivers and in ear insertion meaning zero soundstage. Well this is the first iem that changed my mind. Not saying these can sonically beat headphones but it is close and due to its portability, headphones weightiness, and the uncomfortable pressure headphones apply on/around my headphone, I find that I reach for the Xiaomi's more often than my headphones.

Overall: the sound signature is slightly on the 'bright' side with a slight 'U' sound signature. Relativity wise, highs are most prominent followed by sub-bass. Mids (vocals) and mid-bass follow close to the sub-bass. Anymore detail in the highs and these might sound harsh. I see other reviews of the Xiaomi Pro HD (which apparently sounds the same as the Xiaomi ANC) which say it sounds a little harsh due to the brightness. This may be true for treble sensitive people at high listening volumes but personally as a low volume listener i don't find it harsh. I'm currently using foam tips with them as they help reduce the bright highs which can get fatiguing over long listening sessions. As a result, the bass also sounds more forward and lively which i really enjoy. Although mids become a bit softened and less crisp with the foam tips.

One of the best thing about the Xiaomi’s is that they sound exactly the same regardless if ANC is on or off. Deterioration of sound when ANC is turned on/off is a big problem with pretty much all ANC headphones/earphones so hats off to Xiaomi.

Highs + mids: The Xiaomi ANC have exceptional detail and clarity thanks to the excellent mids and highs. There is plenty of detail thanks to the prominent and far extending highs, yet Xiaomi has managed to keep the highs just below the point of sounding harsh. Looking at the frequency graph (thanks to 'the phonograph' review), there is a spike at around 12k which might explain why the iem is on the verge of harshness and why the highs sound so detailed plus airy.

Cymbals and high hats have very good detail and do not sound splashy, sibilant, or harsh. The highs especially high hats and cymbals have this transient airy sound which is probably thanks to the BA's. This is my first iem with BA's so i enjoyed this new transience very much though that kind of sacrificed the naturalness which dynamic driver excel at. With dynamic drivers, cymbals have that natural 'splash' sound but with these iems its more transient, so has a little 'tsss' sound to it. Perhaps the 12k spike could be attributed to the 'tsss' sound. Basically they don't really have the natural long cymbal decay you'd get from a pure dynamic driver iem. Personally, I think vocals are the biggest star here. The vocals are well balanced among the rest of the frequencies and sound very clear and natural. Overall vocals are a little laid back in quantity, probably due to the more prominent highs and sub-bass, but quality wise vocals are very clear and detailed. I find iem's with vocals that are too forward sound unnatural. Acoustic guitars sound very clean and clear. Every sound can be heard such as the fret sound, the initial pluck sound, and fingers rubbing/hitting the strings.

REMINDER: I listen at low volumes hence i prefer iem's that are a bassy since bass quantity lacks at low volumes. If you have not read the beginning paragraphs of this sound section please go back and read it.

Bass: Through listening and examining the frequency graph, the bass is evidently sub-bass oriented as it peaks at around 30Hz. Personally i like my bass to be elevated quite evenly, perhaps slightly mid-bass oriented.
I was initially disappointed by the bass though. It sounded quite soft, especially the mid-bass which sounded like it had no power. Kick drums sounded damp, as if someone draped a dense piece of cloth over the front and back of the drum and barely put any pressure on the pedals. BUT I have now (after 1 month) realised why it sounded so bad. I did not insert the ear tips in deep enough to get a proper seal as the oval tips felt kind of weird at first. I also recently swapped my right ear tip for a smaller one as I found that my right ear is smaller than my left. This meant I was not able to get a proper seal for my right ear before.

My ears are now fully accustomed to the ear tips shape, so I find them very comfortable and can 100% seal. I think burn-in both physical and mental might have also increased the bass but i am quite certain it was just the seal. Bass sounds better now, sub-bass is alright for me and extends very deep but mid-bass, although better, is still a little soft and lacks that punchiness and boom. This lack of midbass is evident inithe frequency graph as it rolls off too rapidly from sub bass to mids. The rapid mid bass rolloff could also be the reason why mids (vocals) sound so clear albeit more on the thin side. Compared to other dynamic phones, i have to say the mid bass is a little slow/loose and a little damp. At around 30%+ of max volume bass quantity comes out alot better so if you are not a low volume listener then bass quantity should be fine, if not a little emphasised in the sub bass. I have recently compared the bass with my Sony mdr1A and Sony mdr-zx600 headphones and found that the bass in the Xiaomi’s are softer than the two headphones. Sub bass is around 85% of the Sony headphones while mid bass is around 70-80%. However, the bass does not affect the mids or highs i.e. no bleeding. The Xiaomi really are an all-rounder which excels in everything I’ve listened to whether it be EDM, jazz, rock or classical music. Sometimes i do wish for more bass when listening to EDM but i find the rather subdued bass good for long listening sessions. The Sony headphones elevated bass becomes ungainly after around 30 minutes of listening. Bass is like fat, moderate amounts adds flavour and richness but eating it continuously will make you feel sick.

Soundstage + imaging: Now getting back on track, the Xiaomi’s sound airy where every instrument and vocal has lots of room to ‘breathe’ and imaging is very good. It’s as though you’re being surrounded by drawers and every instrument has its own compartment. Left/right separation is great, width is good for an iem, but depth and height is not that great as expected with iem’s. Overall soundstage is good for an iem as music sounds like it comes from slightly away from the ear.

End words: Overall, for sound I would give the iem an 8.75-9 out of 10. These have the potential to be a 10 by further improving the soundstage, instrumental separation, and most importantly bringing out the midbass more plus increasing its speed. I am ok with the current mid-bass given that the decent sub-bass kind of compensates for it, but mid-bass just feels like they lack a bit of power, like the dynamic drivers can’t drive it to its full potential. It’s like a piano, the tone sounds best when you press the key deeply and at a moderate to moderately loud volume. If you press shallow or too soft or too loud the tonality will not sound as good. This is how I feel about the mid-bass, the Xiaomi’s slightly lack that drive.

I have tried blocking the vent hole near the nozzle in hopes of increasing bass but found that the drivers could not produce any sound. This also meant that the slit at the bottom of the housing is not a functional vent but merely for aesthetics.

Isolation and noise cancellation:
NOTE: this has been updated

Isolation is average though even at my low listening volume i can barely hear other people speaking in the same room or ambient noise, that's if i'm not completely focusing on it. The long 'vent slit' at the bottom of the housing is actually not a functional vent as i have tried blocking the vent hole near the nozzle and found that it created a 100% seal as the driver could not produce sound. Noise cancelling only blocks out the bass-low mid-range frequencies from 50-1500Hz as specified by Xiaomi. Xiaomi claim a >20db reduction of noise which I find true. Keep in mind that a 10db noise reduction is a 50% reduction in perceived loudness. They won’t be as good as the Bose QC series but the noise cancelling is definitely noticeable and worthy of use, unlike other cheap ANC earphones such as the $20 Bluedio which offers near zero cancellation. I find it very useful on trains and buses where the ANC really help reduce the low frequency grumbling engine and air conditioner noise. This way I could maintain the same volume yet hear the bass which would usually be drowned out by the low frequency noises. I have also blasted airplane cabin noise on my sound system and found that the ANC performed quite well. Testing ANC on the plane went well with a very noticeable reduction in noise. Usually i'd have to blast my phone volume at 50% to hear decent bass on the plane but with the ANC I was able to hear all the musics detail at my normal low volume (20%). There are 2 levels of noise cancelling (low, high) but I don’t see any use for it as the high-level ANC is already not that great anyways. The ANC barely blocks out any human voice or high frequency noises but the passive isolation does a decent job at that anyways. Xiaomi claims the battery life lasts 12 hours, but the longest I’ve used them for on ANC is 7 hours so I cannot verify this. To sum up, if the Bose QC headphones block out 90% of noise, these block out 40-70% since it cannot block out the high frequencies. Though I have tested it on bass heavy music and can confirm that it can cancel around 80-90% of the bass.

Comparisons:

UPDATE: if you're a budget basshead, i would highly recommend the Plextone X41M instead of both the Piston and Remax below. Plextone has the same forward sounding vocals as remax and prominent highs but with amazing sub woofer like bass, perhaps even stronger than subwoofer! Great thing is it does not really affect the mids and highs. Even for non bass heads i'd probably recommend these over both the iem's below, an extra dollop of bass never hurts. Seal and hence isolation is exceptional. Look out for a review.

- Remax S1 Pro ($10 USD):
The Xiaomi’s sound more refined than the Remax which cost 4-5 times less though perform similarly to the Xiaomi’s and very well for the price. Both have similar sound signature and are slightly more on the 'bright' side. Note that that the Remax only has one dynamic driver while Xiaomi has 2BA+2DD. The biggest differences is the airiness, separation and soundstage which the Xiaomi’s excel at while with the Remax everything sounds like it’s in your head. Left/right separation is also notably better with the Xiaomi’s. Tuning is like the Xiaomi’s with good balance of bass, mids, and highs where the latter 2 are not recessed at all. The high’s especially cymbals and high hats sound splashy, a little too forward, and harsh compared to the Xiaomi’s. Vocals on the Remax do not have as much airiness or room to breathe and sound a tad more grainy and unrefined. Vocals do sound more forward than on the Xiaomi. Bass wise they both perform very similarly with roughly the same quantity of bass though Remax’s bass esp. sub-bass sounds a bit unrefined, loose, and lacks that punch when compare to the Xiaomi. The Remax also overwhelms or bleeds into the mids by a tiny amount. I personally find its mid-bass a bit more punchy and likeable than the Xiaomi’s. Remax also has a wearing style that hooks over the ear so has a more stable fit. Its profile is also much smaller than the Xiaomi allowing it to rest in the ear thus you can sleep sideways with it. The biggest downside of the Remax is that when using it with my phone (Xiaomi 4x), it hisses whenever something is being played which ruins soft recordings such as classical music. I suspect this may be a source error as the hissing does not occur when playing music from my computer. Also there is no vent which meant i was not able to insert the iem deeply and create a full seal as that meant the dynamic drivers would not work. This caused the iem to fall out easily, especially considering my ear is small and is already pushing against the housing.

As a result i really would NOT recommend this iem unless you are using foam tips which probably lets some air in and acts as a vent but i have not tested this yet since i do not own foam tips. Otherwise if you have foam tips and are very short on money and/or want something that you can work out with due to its stability and cheap replaceability as you’ll be bashing these around, then get the Remax. Or you listen to music while sleeping which I don’t recommend unless you have some condition where music may help you sleep.

Overall the sound quality differences are quite small, but I would highly recommend the Xiaomi’s. Not only do you have a more refined sound with better soundstage/imaging, but also a noise cancelling iem for commuting.


- Xiaomi Piston Fresh version ($5 USD):
The Piston fresh sounds like it has a stronger bass quantity than the Xiaomi ANC’s. Though I suspect the two have the same amount of bass, just the Pistons highs and especially mids are recessed quite alot compared to the Xiaomi ANC thus giving an illusion of more bass. When compared to the Xiaomi ANC’s, the Pistons are definitely ‘V’ or ‘L’ shaped sounding with strong bass and recessed highs and especially mids. This makes it sound very fun with electronic and other bass heavy music. It can also be less fatiguing thanks to the recessed mids and highs though I do not find the Xiaomi ANC’s fatiguing at all. Unlike other dirt cheap iem’s that also suffer from recessed mids and highs, the Pistons highs and mids sound smooth and rather refined. Due to it being recessed and smooth, micro details will be missing. Like the Xiaomi ANC’s, the Pistons are also well built with a nice silicon cable and a machined metal driver housing.

If you’re on a very tight budget and are looking for something that you can thrash around yet sound smooth, un-fatiguing and has a good amount of bass then get the Pistons. For budget bass lovers who also like their mids and highs, get the Plextone X41M.

Otherwise I would highly recommend the Xiaomi ANC’s which have much better mids and highs plus you get active noise cancelling. For those on a budget who appreciate their mids and highs, get the Remax S1 Pro.


Possible improvements:

Summary:
Would I recommend these? If you are a basshead or even a bass lover then i might avoid these. Otherwise i'd most definitely recommend it!!! Even as a bass lover myself, the airiness and clarity of the mids and highs won me over. This thing just oozes value. For $42 the drivers don’t spit out sound, they spit out dollar bills. Even if you don’t commute these might be worth it just for the sound, especially for those who love clear mids and highs. Unlike the BOSE QC series which deteriorates in sound when used in passive mode, the Xiaomi’s still sound great when used passively. As a commuter I find it a big safety feature as I can listen in passive mode to increase my awareness when on night trains or walking on busy streets. Yet I don’t need to sacrifice sound quality.
Overall i rate the iem a 4.25 to 4.5 out of 5. Build is excellent, mids and highs are airy with good detail plus clarity, ANC is effective (within Xiaomi's specified frequency range) with no sound quality loss, soundstage plus imaging is good for an iem, and all of that for just $42USD. The only real thing holding it back is the soft bass, especially midbass which is also a bit slow and damp.
Finally hats off to Xiaomi for creating such a fine ANC iem at an insanely low price!