Tanchjim Fission IEM

Tanchjim Fission: The Ultimate Tuning Playground

The Tanchjim Fission represents a very exciting offering in the IEM market, with unprecedented versatility through its various tuning options; and for someone who loves tuning their audio experience; it is one IEM I was very excited to get in for review. With interchangeable nozzles, a tuning dial system, and DSP in the provided usb-c adapter, the Fission delivers what is probably the most customizable listening experience in any price range.

But beyond the tuning options make the Fission particularly compelling; one is how it brings the premium DMT5 dynamic driver technology from Tanchjim’s higher-end Origin model to a more accessible price point.

I first came across the Fission at Munich High-end, while chatting about EQ with the Tanchjim representative, he said you have to try this new IEM, and as someone who loves to tinker with the sound of the audio products, I was immediately smitten with the Fission.

Because there are many different tuning options, Tanchjim marketing material talks about 4 sound modes and 12 different profiles, but actually I feel there are many more options, especially when you factor what is available within the Tanchjim App.

So this review will be a little different as I thought it is better to go through each tuning option and talk a little about the subjective experience you can expect when using each of the sound modes but show some measurements for each sound mode.

But before I get into that section, let’s look at the look at the unboxing experience.

Unboxing and Build Quality

The Tanchjim Fission comes in a compact but well-designed package that efficiently houses the IEMs and their accessories:

The back of the box provides detailed specifications and feature information:

Removing the outer sleeve reveals the inner packaging:

I really like the packaging with the Fission; basically you get various layers revealing more aspects of what is offered with the Fission:

The top layer contains the eartips and soft carrying bag:

I do like the soft carry bag; it is actually something I would use rather than the larger ‘jewelry boxes’ that come with many IEMs in this price range:

Here’s a closer look at the top layer contents with the various eartip options:

The second layer reveals the IEMs and alternative nozzles:

Finally, at the bottom level the cable and the various adapters are neatly packaged in their own compartment:

Inside the box, you’ll find:

• Tanchjim Fission IEMs
• Modular cable with three interchangeable plugs (3.5mm, 4.4mm, and USB-C DSP)
• Three sets of tuning nozzles (S: Standard/Stainless Steel, T: Titanium, C: Copper/Brass)
• Six pairs of eartips (narrow and wide bore in S/M/L sizes)
• Carrying pouch
• Tuning screwdriver
• Documentation

Build Quality and Design

The build quality of the Fission is excellent, featuring full metal shells with a matte finish that prevents fingerprints and scratches. The rose gold/champagne color gives them a premium appearance, while the glass faceplate with subtle branding adds a touch of elegance.

Here are the shells from different angles, showing the premium construction:

The shells are remarkably lightweight despite their metal construction, and the overall design feels durable and well-engineered. The tuning switches are clearly visible on the inner face of each shell:

The included screwdriver makes adjusting the tuning switches straightforward:

Cable and Connectivity

The modular cable is a standout feature, offering flexibility in connectivity options while maintaining good build quality with minimal microphonics:

The cable is ergonomically shaped for comfortable wear around the ear:

The 2-pin connectors feature easy-to-see color coding:

The cable uses a 4-pin design that supports the full range of connectivity options:

The three adapter types provide ultimate connectivity options:

Here’s a closer look at the adapter connector system:

The connector adapter uses a secure 4-pin design:

Fit and Comfort

The Fission features a compact shell design that fits comfortably in most ear shapes. The ergonomic contours allow for a secure fit during extended listening sessions, though the 6.4mm nozzle diameter may be slightly large for users with smaller ear canals.

The Fission comes with two different eartip designs to accommodate different preferences:

Here’s a closer look at the narrow bore eartips:

And the wide bore alternative:

Isolation is decent but not exceptional, which is typical for vented dynamic driver IEMs. Finding the right eartips is crucial for both comfort and sound quality, as proper seal significantly impacts bass response and overall tonal balance.

During testing, I found that the included wide-bore tips provided the best combination of comfort and sound quality, though your experience may vary depending on your ear anatomy. The choice between narrow and wide bore tips also significantly affects the treble response, as detailed in the sound impressions section.

Features and Customization

The Tanchjim Fission’s standout feature is its remarkable versatility through multiple tuning options:

Interchangeable Nozzles

The Fission comes with three different screw-on nozzle filters, each offering a subtle but noticeable change to the sound signature, which I will get to in more detail later:

• S (Stainless Steel)
• T (Titanium)
• C (Copper/Brass)

The alternative nozzles come neatly packaged in the box:

Here are the two alternative nozzles alongside the default:

Tuning Dial System

On the inner face of each earpiece is a tuning dial with four positions that can be adjusted using the included screwdriver. Here is how Tanchim describe of these options, but I have some slightly different opinions later:

• Atmosphere (Default): Provides the fullest bass response
• Pop: Reduces bass for a more balanced presentation
• Natural: Further reduces bass
• Monitoring: Minimal bass for a more analytical listening experience

DSP and App Integration

The included USB-C plug connects to the Tanchjim app, enabling DSP processing with five different default sound profiles, again this is how Tanchjim describe them and this time I think its pretty accurate, but I will get into the details a little later:

• Default: Standard tuning
• Natural: Balanced sound with natural timbre
• Balance: Neutral presentation with precise imaging
• Popular: V-shaped signature with enhanced bass and treble
• Musical: Warm, engaging tuning with emphasis on musicality

The app also allows for custom EQ settings, giving users even more control over their listening experience.

Sound Impressions

The Tanchjim Fission delivers a remarkably balanced and refined sound signature that showcases the versatility of its multiple tuning options. The beauty of the Fission lies not just in its default sound, but in how each tuning modification creates a distinct listening experience while maintaining the excellent technical foundation provided by the DMT5 driver.

I was especially impressed how close the default sound signature is to the already excellent Tanchjim Origin, this IMO is a great starting point for the various configuration options you get with the Fission.

Default Sound Signature

In its stock configuration (S nozzle with Atmosphere dial setting), the Fission presents a beautifully balanced sound that serves as an excellent foundation for all the tuning variations. The default tuning offers a slightly warm-neutral signature with excellent technical performance across all frequencies.

The bass response is clean, controlled, and well-extended, with the DMT5 driver delivering impressive sub-bass extension and punchy, articulate mid-bass. The midrange shines with excellent vocal clarity and natural timbre, while the treble provides good extension and detail without harshness. This default tuning works exceptionally well across all genres and serves as the perfect starting point for exploring the Fission’s customization options.

Eartip Selection: Wide Bore vs Narrow Bore Impact

One of the most immediately noticeable tuning changes comes from the choice between narrow and wide bore eartips, particularly in how they affect the treble response:

The wide bore eartips reduce treble energy, creating a smoother, more relaxed presentation that’s excellent for longer listening sessions. This makes them ideal for genres like jazz, classical, and acoustic music where you want a more laid-back sound. The narrow bore eartips maintain more treble energy, providing better detail retrieval and a more analytical presentation that works well for rock, metal, and electronic music where you want maximum clarity and definition.

The difference is subtle but meaningful—the wide bore tips tame any potential harshness while maintaining good detail, while the narrow bore tips maximize resolution and air. I found myself preferring the wide bore tips for most listening, as they provide the best balance of comfort and sound quality.

Nozzle Variations: Material Makes a Difference

The three interchangeable nozzles also provide subtle changes in the sonic characteristics, with the titanium nozzle offering the most significant departure from the default stainless steel:

Subjectively, for me, the copper nozzle provides a subtle shift toward warmth and musicality.

Stainless Steel (S): The default nozzle provides the most balanced presentation with excellent all-around performance. This is the nozzle I’d recommend for most listeners as it showcases the Fission’s natural tuning without coloration.

Titanium (T): Offers more midrange presence with slightly less bass impact. The titanium nozzle enhances vocal clarity and brings instruments slightly more forward in the mix. While the other two nozzles are very similar, the titanium provides a more analytical, detail-focused presentation that works particularly well for vocal-centric music and acoustic genres.

Copper (C): Provides the warmest presentation with slightly tamed treble and a fuller, more musical sound. The copper nozzle is excellent for those who prefer a more relaxed, easy-going sound signature that’s forgiving of poor recordings while still maintaining good technical performance.

But compared to the tuning switches and especially the DSP options available with the usb-c, these changes are subtle.

Tuning Switches: This is really a Bass dial

The four-position tuning dial system provides significant control over the bass response, though my recommendation is to mostly leave it at the default Atmosphere setting:

Atmosphere (Default): Provides the fullest, most natural bass response that works well across all genres. This setting gives you the complete low-end extension and impact that the DMT5 driver is capable of.

Pop: Reduces bass for a more balanced presentation. This can work well for pop music and genres where you want vocals to be more prominent, but I found the default Atmosphere setting to be more engaging overall.

Natural: Further reduces bass for what Tanchjim is calling a more neutral sound, but this seemed too rolled off in my opinion. So, While potentially creating a more analytical presentation, it sacrifices some of the musicality and engagement that makes the Fission special.

Monitoring: Provides minimal bass on recommended for those you hate bass. This setting is very lean and removes much of the warmth and body that makes music enjoyable. Possible useful for critical analysis but not recommended for regular listening.

Unless you specifically want a rolled-off bass response for analytical purposes, the Atmosphere setting provides the best balance of technical performance and musical engagement. The bass reduction in the other settings is quite significant and can make the sound feel thin and less engaging.

USB-C DSP: Digital Enhancement and App Integration

The USB-C DSP functionality opens up an entirely new dimension of customization through the Tanchjim app, providing both preset options and custom EQ capabilities:

Lets start with the default analog compared to the default DSP default:

But my personal favourite was the natural preset:

The “Natural” DSP preset represents one of the best USB tunings available, offering a relaxed presence region that maintains excellent detail while reducing any potential fatigue. This preset demonstrates how digital processing can enhance the already excellent analog performance of the Fission.

But there are lots of very decent DSP preset options:

Tanchjim App Experience

The Tanchjim app provides an impressive array of customization options that can transform your listening experience:

The app’s home screen provides easy access to all the key features, including preset selection, custom EQ, and community-shared profiles.

The official presets cover a wide range of listening preferences, from the balanced “Natural” setting to more specialized options for different genres and use cases.

The custom PEQ editing interface is intuitive and powerful, allowing for precise frequency adjustments. A little time spent with the app can provide amazing benefits, letting you fine-tune the sound to your exact preferences or compensate for specific recording characteristics.

The community aspect is particularly valuable, with users sharing their custom EQ settings for different genres, artists, or listening preferences. This creates a collaborative environment where you can discover new ways to enjoy your music.

Gaming presets are also available, optimized for spatial awareness and competitive gaming scenarios.

The Fission-specific settings page allows you to save multiple profiles and quickly switch between different configurations depending on your listening needs.

The DSP functionality essentially gives you access to multiple high-end IEMs in one package. Whether you want a warm, musical sound for jazz, a bright, analytical signature for classical music, or a V-shaped profile for electronic music, the app can deliver it all while maintaining the excellent technical foundation of the DMT5 driver.

Soundstage & Imaging

Across all tuning configurations, the Fission maintains good spatial characteristics. The soundstage is surprisingly spacious for a single dynamic driver IEM, with good width and depth that creates an immersive listening experience. Instruments are well-positioned within the soundstage, with precise imaging that allows for easy location of individual elements in complex mixes.

The layering and separation remain excellent regardless of tuning choice, maintaining clarity even in busy passages. This technical capability is particularly evident in orchestral pieces and complex metal tracks, where the Fission maintains composure without congestion across all its various configurations.

Comparisons

Tanchjim Fission vs. Tanchjim Origin

The Fission shares the same DMT5 driver technology as the more expensive Origin, and the sonic similarities are apparent. Both offer excellent technical performance with natural timbre and engaging presentation. The Origin provides slightly more refinement in the upper treble region and marginally better detail retrieval, but the differences are subtle:

Considering the significant price difference, the Fission represents remarkable value, delivering approximately 90% of the Origin’s performance at a much lower price point. For most listeners, the Fission will be the more pragmatic choice, especially given its additional tuning options.

Tanchjim Fission vs. KE4 and Truthear Pure

The Fission’s tuning flexibility allows it to compete directly with popular reference IEMs in its price range.

Here’s a frequency response comparison showing how a custom Fission tuning positions itself relative to the KE4 and Truthear Pure, specifically I added both my favourite “natural preset” and creating a custom “JM-1 with bass boost” PEQ present. Both of these DSP presets gave me that “new meta” tonality, though not “exactly” the same.

This comparison demonstrates the Fission’s ability to bridge different tuning philosophies. The custom profile shown provides:

• Less bass emphasis than the KE4: Offering a more neutral low-end presentation while maintaining warmth and body
• More bass presence than the Truthear Pure: Avoiding the ultra-neutral approach that some find too clinical
• Balanced midrange: Maintaining natural vocal presentation without the potential shoutiness of some competitors
• Controlled treble: Providing detail and air without harshness or fatigue

The beauty of the Fission lies in its adaptability, if you prefer the KE4’s warmer signature, you can adjust the bass switches and DSP settings accordingly. If you lean toward the Pure’s more neutral approach, the Fission can accommodate that preference as well. This flexibility makes it a compelling alternative to purchasing multiple IEMs for different listening preferences.

Specifications

Specification	Detail
Driver	10mm DMT5 Dynamic Driver
Impedance	16Ω ± 10%
Sensitivity	126dB/Vrms
Frequency Response	8Hz - 48kHz
THD	< 0.056% @ 1kHz
Cable	2-pin 0.78mm, modular plugs (3.5mm/4.4mm/USB-C)
Nozzle Diameter	6.4mm

Measurements

The Fission’s measurement performance showcases the versatility and technical capability of the DMT5 driver across its various tuning options.

FR with channel matching

One thing that I didn’t talk about earlier, but it does contribute greatly to that excellent sound stage and imaging is the channel matching, which is excellent:

As you can see, this is another excellent aspect with the Fission.

Comprehensive Measurement Overview

I did a lot of measurements of each of the various tuning options that I presented earlier.

But here are the raw measurements just showing the breath of different tuning available: 

You might be wondering if I feel there is the best tuning. Especially given the number of configuration options, if I feel both the default tuning and the “natural” usb-c DSP preset are both probably the best ones to evaluate first.

But as I mentioned earlier; the great thing is you can start with either of these, and if you want to tweak the bass or the treble, there are simple options without needing to go into the mobile app to get some subtle (or not-so-subtle changes), then eventually jump into the App and the almost infinite options available via DSP.

Distortion Performance

The Fission demonstrates excellent distortion performance in both analog and USB modes:

Analog Mode Distortion:

And as a percentage:

USB Mode Distortion:

And as a percentage:

The distortion measurements show exceptional performance in both analog and USB modes, with minimal distortion across the frequency spectrum. The USB mode shows slightly better performance in some areas, demonstrating the benefits of the digital processing capabilities.

Rating

The Tanchjim Fission earns a 5-star Pragmatic Rating due to its exceptional versatility, sound quality, and value proposition.

Here’s the breakdown:

• Sound Quality: ⭐⭐⭐⭐⭐ (Excellent balance, detail, and natural timbre)
• Build Quality: ⭐⭐⭐⭐⭐ (Premium materials and construction)
• Features: ⭐⭐⭐⭐⭐ (Unmatched versatility with multiple tuning options)
• Comfort: ⭐⭐⭐⭐ (Good ergonomics, though nozzle size may not suit all users)
• Value: ⭐⭐⭐⭐⭐ (Exceptional performance for the price)

The Fission is ideal for:

• Audiophiles who enjoy experimenting with different sound signatures
• Listeners who appreciate natural timbre and vocal presentation
• Metal and rock enthusiasts seeking technical performance and detail
• Those looking for a versatile IEM that can adapt to different genres
• Budget-conscious buyers who want flagship-adjacent performance

Conclusion

The Tanchjim Fission represents a unique IEM, both bringing some excellent driver technology from the higher end Origin and a crazy amount of tuning flexibility to a mid-range price point. Its combination of excellent sound quality, versatile customization options, and solid build quality makes it one of the most compelling offerings in its category.

There is very little to nitpick about the Fission, maybe the nozzle filters are not as different sounding as they should be and probably all the tuning switches ruin the bass, but the Fission delivers performance that rivals IEMs costing significantly more.

For those who value versatility and sound quality above all else, the Tanchjim Fission represents an exceptional value and earns my strong recommendation.