The Moondrop Harmon is the second product in the XTM complex frequency crossover technology series, positioned in the mid-to-high-end market with an official price of $350. Its core innovation lies in the coaxially stacked three dynamic drivers and four-cavity frequency crossover technology – three full-size 10mm dynamic drivers are built-in.

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Appearance Design & Comfort Fit

Moondrop Harmon is made of resin cavity and metal panel, and the geometric cutting design continues Moondrop’s consistent design language in pure dynamic IEMs.

The metal panel and the 3D printed shell are perfectly spliced and the overall weight is light. The panel has 9 planes at different angles, which can refract quite exquisite light and shadow effects under light.

The earphone cavity is relatively small but has a long nozzle, resulting in a fit that isn’t the most snug but remains stable. The front cavity structure is complex, but the size is well-controlled.

It is good for medium-large ears and does not create stress on the edges of the cavum concha. The wear depth is deep, and users with smaller ears may feel fatigue. The wearing of small ears will look more “suspended”.

Acoustic Configuration & Cable

Moondrop Harmon uses three full-size 10mm dynamic drivers to achieve phase consistency through four-cavity frequency crossover technology. Among them, two horizontally opposed drivers handle bass, while a glass-dome composite diaphragm driver is responsible for mid-high frequency.

This physical frequency crossover structure reduces the size while addressing the transition issues of multiple dynamic drivers, and has been certified by a Chinese invention patent.

The cable material is not specified in detail, only 4-strand hybrid braid wire is known to be. The cable has a special fabric shielding net, which is relatively soft.

The detachable cable system uses a 0.78mm 2PIN connector with a groove design. The pins have strong damping, so you need to pay attention when pulling out/inserting.

The interchangeable plug system is based on a 4PIN structure with a groove and a screw-lock mechanism. The package includes both 3.5mm single-ended and 4.4mm balanced plugs.

Sound Quality & Driving

The impedance is 19Ω and the sensitivity is 114dB/Vrms. Judging from the data, it is relatively easy to drive, but in fact it requires a higher driving force. It is recommended to use a mid-to-high-end player or a decoding headphone amplifier(such as FiiO KA13) – the amplifier need to turn on high gain.

Moondrop’s official optimization solution: Pairing with the FreeDSP Pro decoding cable (single crystal copper wire + CS43198 chip) can unlock its full potential, allowing for personalized tuning via the app.

Bass: Moderate in quantity, and the thickness and fullness are controlled in a relatively suitable state. The bass is punchy and layered, with deep extensions and natural overtones. The retraction and release speed is moderate and there is relatively little reverberation. The sub-bass is very prominent and maintains a very strong presence without affecting other frequency bands too much.

Mids: The vocals are relatively forward, with moderate thickness and well-controlled sibilance. The texture and line sense of the vocal are balanced. The tendency between male and female voices is not obvious. Without affecting the transparency, the listenability of the vocal is relatively high.

Treble: Moderate in brightness, smoothness is sufficient. The treble extension is natural, instrument overtones are rich in detail, and transparency is high. The sub-treble extension is good, with a slow roll-off. Thanks to the glass-dome diaphragm, the overall resolution is high while avoiding irritation.

Soundstage: The horizontal soundstage is wide, the vertical layers are clear, and the dynamic performance is excellent, especially suitable for large-scale classical music and live recording. The separation between vocals and instruments is excellent.

Conclusion

Moondrop Harmon’s standout feature is its ability to break the stereotype of traditional multi-driver in-ear monitors (IEMs) having bloated bass, with its bass control and overall balance earning widespread acclaim. The downside is that it requires a high-powered player or decoding amp to fully unlock its potential.