I’m still one of those musicians who performed with large stage monitors (wedges). For over 20 years, however, in-ear monitors, or IEMs for short, have been the standard for monitor sound on stage. They allow you to move freely around the stage, have the same good sound everywhere and have your own personalised monitor mix. Musicians often wear these in-ear headphones in dazzling colours, gold-plated or discreetly matched to their skin colour.
Almost completely unnoticed, IEMs have also gained a firm place among music listeners. This is not least due to the fact that excellent IEMs made in China are now available for less than โฌ50. In the past, you had to pay โฌ300 or more for a reasonably decent pair. Of course, there are also high-end IEMs today that can cost โฌ3000, but the sound quality of many inexpensive models has nothing to hide.
I discovered these and other inexpensive IEMs when I was looking for in-ear headphones for travelling. Of course, I also went for wireless earbuds first, namely the Sony LinkBuds S, which I liked much better than their big brother, the Sony WF-1000XM5, and far better than the Apple AirPods II Pro.
With active noise cancellation, hands-free function and transparency mode, wireless earbuds are extremely practical and comfortable for everyday use. However, I was still missing something in terms of sound, which made me try wired IEMs. Now I have some excellent headphones in my studio, like the Beyerdynamic 770 and 900 HD, Sennheiser HD600 or an Audio-Technica M50x, but I gave the cheap IEMs a chance. So much for now: I was more than amazed. This is not least due to the fact that many IEMs have been trimmed to the so-called Harman curve.
What is the Harman curve and what does it have to do with headphones?
The Harman Curve is a frequency response developed by Harman International that aims to define the ideal balance and sound for headphones. It is based on extensive research and user studies that indicate how different people perceive the “best” or “most natural” sound.
The Harman curve attempts to create a sound signature that corresponds to a natural listening environment, as if you were listening to music live in a natural setting, such as a living room. It slightly emphasises the low frequencies (bass) and the high frequencies (treble), while keeping the mid frequencies relatively flat. This is intended to produce a warm and clear sound quality that is pleasing to a wide range of listeners.
The function of the Harman curve in headphones is to give manufacturers a target frequency response to aim for when developing their products. Headphones that follow this curve should provide the listener with a more balanced and realistic sound experience, regardless of music genre or recording quality.
KZ Castor in-ear monitor
One of the leading Chinese manufacturers is the company KZ, which means Knowledge Zenith. Admittedly, the abbreviation is anything but ideal in the German-speaking world, but what the heck. In addition to IEMs, KZ also produces wireless headphones (TWS) and normal headband headphones.
The KZ Castor IEMs cost just โฌ26 and you get very high-quality looking IEMs with a pleasing design, 3 pairs of silicone ear tips (plugs) and a pair of memory foam ear tips. They also come with a fairly neat cable with the usual 2-pin connectors and a 3.5 mm jack plug.
The KZ Castor IEMs are trimmed to the Harman curve and have a very balanced sound profile. The bass is powerful but controlled, which is probably due to the design of the Castors with their dual drivers.
The treble range is brilliant without being overpowering. I particularly like the important mid-range, which is very precise and reproduces voices, guitars and other instruments very well. The sound stage is also excellent and open.
A special feature of the KZ Castor IEMs is the tuning option via 4 dip switches (this used to be called a mouse piano among electronics engineers). This allows the sound signature to be customised once again.
Switch 1: 1 dB bass boost
Switch 1 2: 2 dB bass boost
Switch 3: 1 dB in the mid and treble range
Switch 3 4: 2 dB in the mid and treble range
I like the variant with 1 2 activated best and it is probably a little closer to the ideal Harman curve.
In practice:
Like almost all IEMs, the KZ Castor work very efficiently and are easy to control. The volume levels that can be achieved with these IEMs are remarkable. However, they show surprisingly little tendency to distort. The impedance is 16-20 ohms and the sensitivity is a remarkable 103 – 105 dB (depending on the switch configuration).
I currently prefer the foam eartips as they are very comfortable, adapt perfectly to the ear canal and also provide an excellent seal against ambient noise. The castors can also be worn for a long time without pain or pressure. As I like to record guitar and bass with headphones, I now prefer IEMs. You don’t get “hot ears” and the amazingly deep yet crisp bass reproduction, with very analytical mids at the same time, is simply fun. Especially when recording bass tracks, the IEMs almost give me the feeling of playing with a bass amp and speakers.
It’s more than amazing how good headphones can be for less than โฌ30. This is also evident when listening to music with a smartphone. The sound of the Castors and other IEMs is simply fun. The reproduction is more precise than with wireless headphones and I can hear details that I have not been able to discover with my other headphones so far.
As I can now fully appreciate the sound signature of the IEMs, I see no reason why they shouldn’t be used for mixing.
Linsoul CCA Trio IEMs tested
The CCA Trio IEMs are also made by KZ and sold under the brand name Linsoul. At around โฌ42, they are significantly more expensive than the KZ Castor IEMs, but have 3 dynamic 8 mm drivers. Like the Castor, the CCA Trio also have 4 dip switches for individual sound adjustment. The cable is of a higher quality than that of the Castor and overall they have an even higher quality finish.
In terms of sound, the CCA Trio are a little more balanced than the KZ Castor. The upper bass range is a little more subdued, but I have the feeling that the sub-bass is even more powerful and crisp. The Trios are also a little better in the mid-range and the treble range is a little smoother. The KZ Castor are a bit more of a “fun maker” here, while the Trio go even further in the direction of neutral reproduction.
The CCA Trio also seal off sound from the outside a little better (with the same ear tips) than the Castor – at least to my ears.
- Zwei Versionen von KZ Castor: Der KZ Castor KZ In-Ear-Monitor ist in zwei Versionen erhรคltlich: Harman Target und Harman Target mit verbessertem Bass. Beide folgen strikt den Einstellstandards der Harman FR-Kurve, egal ob es sich um die Leistung der Parameter oder die Klangwahrnehmung handelt, sie รผbertreffen die meisten Flaggschiffe anderer Marken
- Innovative gestapelte dynamische Dual-Treiberstruktur Der: KZ Castor In Ear Monitor Kopfhรถrer ist mit einer innovativen dynamischen gestapelten Dual-Treiberstruktur ausgestattet. 200 Hz-Bereich fรผr kraftvollen Bass, wรคhrend der andere fรผr mittlere und hohe Frequenzen sorgt. Die kabelgebundenen Kopfhรถrer von Castor bieten kraftvolle, energiegeladene Bรคsse und hervorragende mittlere und hohe Frequenzen mit diesem prรคzisen elektronischen Crossover-Design
- Harman Target-Version: Die In-Ear-Musiker von KZ Castor รผberwachen die Ohrhรถrer mit der Harman FR-Kurve als Stimmziel, die auf der gefeierten Harman FR-Kurve innerhalb der HiFi-Community aufgebaut ist, egal ob es sich um Parameterleistung oder Klangwahrnehmung handelt, sie รผbertrifft die meisten IEM.
- Harman Target mit verbesserter Bass-Version: kz castor iem, maรgeschneidert fรผr Audiophile, die tiefere Bรคsse suchen, basierend auf der harmanischen FR-Kurve, verbessert die Niederfrequenzempfindlichkeit und dynamische Leistung, um ein unaufhaltsames Niederfrequenzerlebnis zu erzielen. Gleichzeitig richten sich die mittleren und hohen Frequenzen nahtlos mit der harmanischen FR-Kurve aus und erleben beispiellose und atemberaubende Superbรคsse.
- ใ๐๐ข๐ง๐ฌ๐จ๐ฎ๐ฅ ๐๐ ๐๐๐๐ ๐๐๐ ๐ – ร๐๐๐ซ๐ญ๐ซ๐๐๐๐๐ง ๐๐ข๐ ๐๐ก๐ซ๐ ๐๐ซ๐ฐ๐๐ซ๐ญ๐ฎ๐ง๐ ๐๐งใKZ, bekannt fรผr seine Expertise in der HiFi-Audioindustrie, hat in Zusammenarbeit mit Linsoul den neuen ZS10 Pro 2 Kopfhรถrer entwickelt. Aufbauend auf dem Erfolg des KZ ZS10 Pro, verfรผgt dieses neue Modell รผber einen 10mm super-linearen internen magnetischen dynamischen Treiber und zwei 31736 Balanced-Armature-Treiber, die die Audio-Prรคzision und Leistung deutlich verbessern. Der Linsoul KZ ZS10 Pro 2 kombiniert ein aufgefrischtes Design mit seinen klassischen Wurzeln und bietet ein optisch auffรคlliges Update.
- ใ๐๐๐ซ๐๐๐ฌ๐ฌ๐๐ซ๐ญ๐ ๐๐๐+๐๐๐-๐๐ฒ๐๐ซ๐ข๐๐ญ๐ซ๐๐ข๐๐๐ซ ๐ฆ๐ข๐ญ ๐ฎ๐งรผ๐๐๐ซ๐ญ๐ซ๐จ๐๐๐๐ง๐๐ซ ๐๐ฎ๐๐ข๐จ๐ฅ๐๐ข๐ฌ๐ญ๐ฎ๐ง๐ ใDer ZS10 Pro 2 ist auf die anspruchsvollsten Musikliebhaber zugeschnitten und verfรผgt รผber einen superlinearen magnetischen dynamischen 10-mm-Treiber, der mit zwei 31736-Balanced-Armature-Treibern gepaart ist. Diese leistungsstarke Kombination definiert Audio-Exzellenz neu, รผbertrifft selbst die hรถchsten HiFi-Standards und erfรผllt die prรคzisen Anforderungen von professionellen Musikern und Audiophilen.
- ใVerbesserte 4BA + 1DD Hybrid-Kopfhรถrer & magnetische dynamische Einheitใ Als aktualisierte Version des KZ ZS10 verfรผgt der Pro รผber selbst angepasste symmetrische Armaturen, darunter zwei 30095-Treiber fรผr Hรถhen und zwei 50060-Treiber fรผr die Mitten. Mit dieser Konfiguration ist der Klang in jeder Hinsicht vergรคnglich, dynamisch und hell. Unter Beibehaltung der bisherigen Leistung werden die Hรถhen dieses Modells รผber 40 kHz hinaus erweitert.
- ใExquisites Handwerkใ Die Frontplatte besteht aus Edelstahl 304, wรคhrend der Hohlraum aus importiertem Harz besteht. Die beiden unterschiedlichen Materialien sorgen nicht nur fรผr eine elegante Optik und einen schimmernden Look, sondern sind auch praktisch und langlebig. Das abnehmbare, vergoldete QDC-Kabel bietet eine vollstรคndige Aufrรผstbarkeit und der Begrenzungsschlitzschutz verhindert erheblich, dass der Stift bricht und verlรคngert die Lebensdauer der Schnittstelle
- ๐๐๐ฌ ๐๐จ๐ง๐ ๐๐๐ง๐ ๐ญ๐ก ๐๐จ๐ง๐ข๐ ๐๐๐๐๐ฅ: Das Tripowin Zonie gilt seit jeher als das beliebteste preisgรผnstige Upgrade-Kabel fรผr IEMs. Aber es ist nicht lang genug, um fรผr komplexere Setups zu passen, wo die Audioquelle weiter weg positioniert ist. Deshalb haben wir diese Upgrade-Version herausgebracht – das Tripowin Zonie 2M Kabel. Es ist eine attraktive Wahl fรผr alle, die zusรคtzlichen Komfort und Flexibilitรคt in verschiedenen Hรถrszenarien suchen.
- ๐๐๐๐๐ฅ ๐รผ๐ซ ๐๐ฎ๐๐ข๐จ๐ฉ๐ก๐ข๐ฅ๐ ๐ฎ๐ง๐ ๐๐จ๐ง๐ญ๐๐๐ก๐ง๐ข๐ค๐๐ซ: Das 2 m lange Zonie-Kabel bietet mehr Bewegungsfreiheit und ist damit ideal fรผr Studioumgebungen, den professionellen Einsatz oder fรผr diejenigen, die nicht so eng an ihre Audioquelle gebunden sein mรถchten. Durch die grรถรere Lรคnge wird weniger Spannung auf das Kabel ausgeรผbt, wodurch sowohl das Kabel selbst als auch die Stecker weniger beansprucht werden und die Lebensdauer Ihrer Ausrรผstung verlรคngert wird.
- ๐๐ฎ๐๐ ๐๐ซรผ๐ฌ๐ญ๐๐ญ๐๐ซ ๐๐ ๐๐๐๐ ๐๐๐ ๐: Der verbesserte KZ ZS10 PRO X Kopfhรถrer ist ein einzigartiger Kopfhรถrer mit jahrelanger sorgfรคltiger Forschung, Entwicklung und Verbesserung. Der neue Kopfhรถrer verfรผgt รผber eine verbesserte Hochfrequenzleistung und maรgeschneiderte Treiber, was eine empfindlichere Transientenreaktion, eine stรคrkere Basswirkung und eine bessere Klangklarheit bedeutet. Auรerdem wurde es aus hochwertigem Material gefertigt.
- ๐๐๐ฆ๐ฆ ๐๐ฒ๐ง๐๐ฆ๐ข๐ฌ๐๐ก๐๐ซ ๐๐ซ๐๐ข๐๐๐ซ+๐ ๐๐ฎ๐ฌ๐ญ๐จ๐ฆ ๐๐๐ฅ๐๐ง๐๐๐ ๐๐ซ๐ฆ๐๐ญ๐ฎ๐ซ๐๐ฌ: Vier individuell abgestimmte Armaturen sorgen fรผr eine atemberaubende Leistung mit kristallklaren Hรถhen, sanften Mitten und kraftvollen Bรคssen, wรคhrend die verbesserte Hybridtechnologie eine hรถhere Empfindlichkeit und eine schnellere Reaktion bei Musik und Sprachanrufen gewรคhrleistet.
Conclusion
For me, IEMs have not only become an alternative to headband headphones – I now use them almost exclusively. The sound and wearing comfort, as well as the isolation from the outside, are simply marvellous. I also use the IEMs for listening to music and even when I’m travelling, when things like transparency mode, hands-free calling or ANC aren’t important.
With accessories such as a small USB-C DAC, you can also connect these IEMs to smartphones, tablets and laptops that no longer have a headphone socket and get excellent sound quality. With the FiiO BTR3K, the IEMs (and not only those) become wireless headphones with hands-free function, which brings even more convenience.
IEMs have one disadvantage: they can develop into a passion for collecting. In various forums and on Reddit, there are quite a few users who have 10 or more IEMs in their collection.
More info:
Linsoul CCA Trio website
KZ Castor website
Letzte Aktualisierung am 2025-07-11 / Affiliate Links / Bilder von der Amazon Product Advertising API
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