CCA DUO - 2 x 7mm Dynamic Drivers IEM

CCA DUO: A Comparative Review



Introduction

Today, I present a slightly different format than usual. Since the CCA DUO ($29 USD) showed a signature very similar to an IEM I often recommend, I wanted to do a purely comparative review. Let's see how the CCA DUO compares to the 7Hz Salnotes Zero ($20 USD).


If you wish to read this review in Spanish, click here

Check out previous reviews here (or in spanish here)


Disclaimers:

• Many thanks to the folks at CCA (especially Duke) for sending me this product to provide my honest opinion.
  • You can find the DUO here: https://www.kztws.com/products/cca-duo (Official KZ Website)
• Analysis over 4 days - Sessions of approximately 2 to 4 hours
• All music used is lossless (Qobuz > 16bit – 44.1kHz)
• Gear Used: IFI Zen Air Can (AMP) + Fiio E10K (DAC) / TempoTec Sonata HD PRO (dongle)

Unboxing, Build & Comfort

But first, a bit about the construction and accessories of the DUO.





CCA DUO: As a sub-brand of KZ, CCA follows its parent brand building technique, featuring a metal faceplate and a transparent resin body (with dark tint). Despite certain similarities, this model is more compact in size compared to releases like the ZVX and the Krila. It houses two 7mm dynamic drivers inside and features the typical QDC-style connector on the outside, which the brand is known for. The nozzle is 5.8mm in diameter.



Cable: KZ cable (silver-plated copper, cable feels thin and it is evident where they cut costs)



Eartips: Three pairs of silicone (Starlines) and one pair of foam tips. Sufficient, and in this case, the foam tips make sense to tame some of the highs.

Comfort: As I mentioned, the DUO is smaller than other current KZ models, so it fits better to the ergonomics of my ear and doesn't protrude much. The provided tips seal properly, with the foam ones offering a bit more isolation than the silicone ones, but both types, when fitted well into the ear canal, tend to block external noises adequately.

Driveability: It doesn't necessarily require a DAC/AMP or dongle (although it benefits from one, as there are several IEMs that are easier to drive), with a sensitivity of 106dB/Vrms (@1kHz) and an impedance of 18 ohms.



Sound Description (vs 7Hz Salnotes Zero)

Scores (TL;DR for those who prefer a more concise format):

• Better to worse (left to right)
• More ">" indicates a greater difference
• "=" is used to indicate that the model on the left and the one on the right are similar in a certain aspect
• ">=" indicates that two IEMs could be similar depending on the song

Comfort: DUO = Zero (both very comfortable for extended use)

Subbass: Zero > DUO

Bass: DUO = Zero

Mids (male vocals): Zero >= DUO

Mids (female vocals): DUO >= Zero (with lower-register female singers, they are similar)

Mids (instruments): Zero > DUO (due to greater naturalness and better balance)

Treble: DUO > Zero (better quality but similar in quantity – DUO sharper)

Resolution: DUO >> Zero

Imaging: Zero > DUO (easier to locate bass)

Soundstage: DUO >= Zero


Observations:


Credits: Audio Reviews News

The extension in the subbass region is good in both sets, but the boost that the Zeros have in that area allows them to not get so hidden in the signature (the DUO's lack is noticeable in songs from the album "Live After Death" where at times the bassist disappears or becomes very difficult to find). For this reason, there is also better differentiation between bass and subbass, although neither of these two IEMs achieves a significant impact in the 80 to 200 Hz range. The CCA IEM's driver is faster compared to the Zero.

While both of them do not have a strong presence in the lower midrange, the lower-register vocal ranges have more authority in the Zeros, making them excellent for singers like Sinatra. For singers with higher-pitched voices like Amy Winehouse, the CCA DUO manages to push these ranges forward just a bit more than the Zeros, giving them the spotlight.

It's worth noting that the clarity of vocal registers is usually higher in the DUO simply due to a lesser elevation in the bass region.

Listening to Megadeth, the sense of definition in instruments like electric guitars stands out more in the DUO compared to the Zeros. However, this certain thinness in the signature makes instruments that can reach higher notes (just like the mentioned guitars) take the spotlight, but in doing so, they lose a bit of coherence in other music genres like orchestras, where higher strings such as violins and violas will always have a prominent place in front of winds or lower strings. Trumpets and violins "compete" for the lead role in "Swan Lake, Op. 20, TH. 12 / Act I: No. 1 Scène (Allegro giusto)."

Despite what was mentioned about the DUO’s midrange, the microresolution is spectacular for its price, and small details in the chorus of "Miss You" are heard with ease and precision. So, the Zero is for those who prefer naturalness or a more balanced sound, while the DUO would be better suited for more analytical users.

I find that the treble at moderate and slightly higher levels are somewhat more exaggerated and piercing in the DUO, but the difference is not immense. To put it in words, the Zeros approach the limit of being strident, while the DUO surpasses it in certain songs. Again, the level of detail here is very good, exceeding that of the Zeros.

The soundstage has similar width and depth (both above average in their respective price ranges). If I had to take a guess, I'd say that the DUO achieves slightly more depth in live albums.

There is a good degree of separation between the instruments reproduced by each pair of headphones, but I have to give the imaging to the Zero. It's not because the Zero has a more capable driver or anything similar, but as I mentioned earlier, the DUO can, on several occasions, make the user lose track of the bassist's location or not provide a sufficient impact in the execution of the drum kicks, affecting the placement of certain instruments.



Conclusion



Does the DUO present a significant improvement to justify the $10 USD price difference? Yes and no. In terms of the driver, it's noticeable that the DUO has a superior capability for reproducing small details that are hard to perceive. However, music isn't solely about the meticulous analysis of sounds, so I also value a proper balance between frequencies and the harmony of the ensemble of instruments. This is where I believe the CCA IEM can't compete with the Zero, and personally, I found myself spending more time with the latter for the enjoyment of my music.

DISCLAIMER

I would like to thank KZ/CCA for furnishing this unit. The Duo can be gotten here (no affiliate links): https://www.kztws.com/products/cca-duo

SPECIFICATIONS

• Driver configuration: 7 mm + 7 mm dual dynamic drivers (no info on diaphragm materials)
• Impedance: 18 ohm
• Frequency response: 20 Hz - 40 kHz
• Sensitivity: 106 dB
• Cable: 2-pin, 0.75 mm, silver-plated cable
• Tested at $29 USD (non-mic version); $30 USD (mic version)

ACCESSORIES

Other than the IEM, the following are included:
- 3 pairs of KZ "Starline" silicone tips (S/M/L)
- 1 pair of foam tips
- Cable

The accessories are pretty lacking, with no case provided. But I guess as it is a budget IEM, costs have to be cut somewhere.




The KZ Starline silicone tips are one of the most ubiquitous tips, and most CHIFI aficionados would have encountered them in their IEM journey. The foamies tame treble and increase isolation, and they synergize well with the bright Duo (we will talk more about its sound signature later); albeit foam tips are not be so durable and may also compress the soundstage.

The stock silver-plated cable, though on the thinner side, is surprisingly quite microphonic-resistant. Unfortunately, it does not come with a chin cinch, and is a bit tangly.

The rest of this review was done with the stock cable and stock starline silicone tips. No aftermarket accessories were used, so as not to add any confounders to the sound.



BUILD/COMFORT



The triangular face-plates are fashioned from 3D-printed metal. They are mirror-like and shiny, but may be fingerprint or scratch magnets. The inner aspects of the earpieces seem to be made of a resin/plastic material, and the shells are light and relatively well-fitting - I have no complaints on the ergonomics.



Isolation is bang average, in view of the vented shells. I did not encounter any driver flex, though this is partially dependent on ear anatomy and type of tips used.


DRIVABILITY

I tested the Duo with the following sources:
- Apple dongle
- Cayin RU7
- Colorfly CDA M1 DAC/AMP dongle
- Creative Sound Blaster X5
- E1DA DAC/AMP dongle
- Hiby R3 Pro Saber 2022 DAP
- Khadas Tone Board -> Schiit Asgard 3 amp
- Khadas Tone Board -> Topping L30 amp
- Questyle M15 DAC/AMP dongle
- Sony Walkman NW A-55 DAP (Walkman One WM1Z Plus v2 Mod)
- Sony Walkman NW A-55 DAP (Walkman One Neutral Mod)
- Sony Walkman NW WM1A DAP (Walkman One WM1Z Plus v2 Mod)
- Smartphone

This IEM is moderately easy to drive, though it scales slightly with amplification.


SOUND & TECHNICALITIES

Graph of the CCA Duo, via IEC711 coupler. 8 kHz is a coupler artefact peak.

Tonally, the Duo can be described as having a bright U-shaped profile.

The Duo is sub-bass focused. The sub-bass extends quite deep with authority and decent rumble, though it is just slightly north of neutral in quantity, and is not for bassheads. In terms of quality, bass texturing is above average with moderate speed, with just a sprinkle of mid-bass bleed.

As per the U-shaped tuning, the lower mids are slightly pulled back. This area is still quite transparent, with no big bad bass to bite into this frequency band. The upper midrange has a 6 dB ear gain, and with no copious bass to balance out this region, female vocals are forwards and just at the edge of shoutiness.

The Duo is a treble-emphasized IEM, and this region has good air and extension. This gives a lot of clarity and resolution, though on the flip-side, sibilance rears it ugly head, and there are over-emphasized cymbals and high-hats heard. Indeed, treble-sensitive folk should stay away, but trebleheads might fall in love with the tuning.



Technicalities-wise, I would class the Duo as above average at its price point. As per the boosted upper frequencies, this brings a lot of resolution and clarity to the mix. Micro-detailing is acceptable, and imaging and instrument separation are quite decent. Soundstage is average in width, but above average in height and depth.

Timbre is sadly a tinge metallic, with an anemic and thin note weight. Vocals can hence sound unnaturally nasal and scrawny as such.


COMPARISONS

Comparisons were made with other budget dual DD sets. Planars, single DDs, hybrids and pure BA types were left out of the equation as the different transducers have their pros and cons.




TRI Star River


Graph of the TRI Star River via IEC711 coupler. 8 kHz is a coupler artefact peak.

The Star River is a dual DD set with 4 purported tuning options. However, on actual testing, there are only 2 distinct V-shaped old-school tonalities (ie switches are a gimmick). The Star River's QC is also a bit dodgy, with one side of the earpieces having stuck switches that require huge force to manipulate.

Compared to the Duo, the Star River is definitely more V-shaped, and has more bass and treble. It is shoutier as such in the upper midrange/lower treble, and is even more fatiguing than the Duo.

The Star River has worse soundstaging, but otherwise has improved imaging, micro-detailing and instrument separation.


Truthear Zero (Original)

The Zero is bassier in the sub-bass, though its bass isn't as tight and clean as the Duo's. Both sets are thin in the lower mids, but the Zero is shoutier in the upper midrange.

Technicalities are weaker on the Zero, it has worse separation, micro-details and imaging.


CONCLUSIONS



The CCA Duo is dual DD U-shaped pair, with above average technical chops. Build, ergonomics and drivability are plus points, though the lack of accessories is disappointing.

Unfortunately, the Duo has some tonal flaws, suffering from a thin note weight with metallic timbre. It is also not for treble-sensitive brethren, due to a bright soundscape with sibilance in abundance. Bassheads may find the bass quantities wanting, but this set goes for quality over quantity in the bass.

In a nutshell, the Duo has some shortfalls (especially in treble and timbral accuracy), but otherwise does more things right than wrong. Actually, I would class it as an above average entrant to the dual DD game. Sadly, it might be forgotten in a few weeks' time, such is the competitiveness of the cut-throat budget CHIFI market, that being average (or even above average) is akin to a death sentence. Or a greater likelihood, is that a pro version of this KZ/CCA might come out mere days after this review is written!

CCA DUO

First of all kudos to CCA taking our suggestion for not using the random 3 letter model name which many fans and enthusiasts like myself can’t keep track on it anymore.

DUO is an IEM you need to take time to appreciate the tuning.
I believe CCA is going for a more mature audiophile tuning rather than an entry level IEM such as the famous CCA CRA.


MID
Mids & Mid bass does sounds rich & lushful making vocal sounding prominent.

BASS
bass doesn’t lingers too long, the bass is fast and quick making is sounds clean & punchy.

TREBLE
Enough treble but not pitchy.
Treble at its comfort zone.


Notes

• It’s frequency of bass, mid and treble very well separated making it sounds good in instrument separation.
• Amount of the bass sounded polite but punchy. Some (fans of heavy bass) might probably say not sufficient enough.

• Suitable for….For work - as both bass and treble not over powered making using long hours comfortable.

Very suitable for night time listening sessions.
Listeners who listens to wide range of different genre music
People who like loud volume listening, it still feels intimate and not ear aching.

• Not suitable for

People who love to have low rumbling bass

• Impressions from random listeners.

Wong - smooth, for vocal, high treble not pitchy.
Agnes (not audiophile) - nice, good sound, pleasant sound.


COMPARISON
The sound signature reminded me of DQ6s hence I dig out from my archive to compare.
DQ6s - more lower frequency bass.
Duo - better treble, better treble detail.
Duo would be the improve version with more definition and more pin point instrument separation.

SeeAudio Yume Midnight
Duo - more treble, natural analogue sounding treble, punchy bass
Yume Midnight - less treble, cleaner digital treble, more smooth velvet sounding bass. Overall sounded more resolving.
Both really comes very very close sounding, Yume Midnight still sounds more resolving and more details presentation overall.
Take note: SeeAudio Yume Midnight uses 1DD+2BA drivers and they are price around USD200.

Blind test, Agnes (non audiophile perspective/impression)
Midnight vs Duo
Midnight - treble better details, bass is define. Vocal less.
Duo - Overall more full sounding. Treble less details, bass & vocal good.


Listening Sessions worth mentioning.


Axel F. Harold Faltermeyer (the bad boys movie theme song) ️️️️️
Song like this sounds perfect bringing out the nostalgic 80’s Roland Synthesizer & Moog.

Plastic Love - Mariya Takeuchi ️️️️
This track is a city pop genre song which have a lot of instruments arrangement together.
I hear very clearly piano and violin playing which I seldom take note before despite listening to this song many times. This exhibits strong mids and great sound separation.

Say So - Japanese Version (tofu beats remix) ️️️
This track is an up beat bassy pop song.
Despite comparing with other IEM which have more sub bass than DUO listening to this track I still felt much satisfaction and enjoyable.

Don’t Stop Me Now - The Regrettes ️️
Bass kicks seems to be overpowered other instrument. Take note this recording approach is those low-fi very analogue sounding contains grainy sounding in it’s recording process (nothing wrong with the IEM)

I have been listening constantly from 2-3 weeks, 3-5 hours a day with all sort of songs and overall it’s been enjoyable average ️️️ to ️️️️

I have been trying out EQ lately with my Wiim Mini.
EQ works very well with DUO brings out different flavours base on your music genre and likings.

Using a more decent headphone DAC/Amp (iFi Zen DAC v2) give you more sense of head room and wider width and better depth sounding.
But in terms of sound signature this pairing makes DUO sounds more warm/darker (compare to my previous Wiim Mini streamer (with flat - no EQ adjusted).
On Zen DAC Duo can handle iFi bass boost featured without any distortion.

Perform well for vocal tracks.

Believe to be tune close to harman tuning sound signature (some research by Harman institute some sort…)

I would IEM can consider a warm natural close to neutral sounding.

Recommended ear tips Moondrop Spring Tip, I tried the foam tip came with KZ IEM it drowns the treble details.



CONCLUSION
If you love smooth sounding this is a good one.
If I buy this with my own money am I happy with this purchase? Yes.
My personal score 7/10



About me:

• I am a IEM hobby enthusiast who started this crazy IEM journey since 2019
• I am not young hence I am not sensitive to treble.
• My audio setup are mostly minimalist setup (iPhone, IPad Pro & WiiM Mini)
• My interest and goal mostly it’s to find great price with great performance stuff.
• I don’t do this to make a living, it’s just pure hobby.
• I usually try my best not to use too in depth technical terms.
• 60-70% of my write up I buy my own stuff, sometimes community friends and dealer and manufacture send me IEM for write up.
• I love taking photos of IEMs (depending on my time).
• CCA sent me this set for my write up, no money involve.

Gear used
- mostly on IPhone & IPad Pro with usb/lightning DAC (BGVP T01s, Avani, Abigail, CX Pro)
- sometimes desktop laptop with iFi Zen DAC / Megatron from VE Electronic.
- Tidal on iOS App, MQA/FLAC.
- WiiM Mini on Tidal.