Hidizs Mermaid MM2 Review 7 e1650808829301

Hidizs Mermaid MM2 Review

Hidizs is a famous brand when it comes to high-performing and budget-friendly HiFi audio gears. Today we are reviewing the new Mermaid MM2 IEM.

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Hidizs has designed a rather unique set with a low-voltage 6mm magneto-static balanced membrane and a 10.2mm dynamic driver on each side. The shells are made up of eco-friendly resin material with lozenge-cut faceplates.

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The newly-developed 6mm magneto-static BM (Balanced Membrane) driver is customized by Hidizs and Korea BSE. This driver uses a lightweight and ultra-thin micron-level diaphragm for the high frequencies.

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Hidizs has also developed a new 10.2mm dynamic driver for the MM2 that adopts PEK macromolecule polymer diaphragm.

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The pair comes with three pairs of Tuning valves (filters) for balanced, bass enhancing, and treble enhancing sound adjustments.

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Hidizs packed the MM2 with a high-quality quad-core cable. The cable has a mixed configuration with two cores of high-purity silver wires and two cores of OFC wires. It has 2-pin connectors and a 3.5mm gold-plated termination plug. The cable is soft, handles very well in the hand and has no microfonics.

What’s in the box


  • 6mm Low-voltage Magneto-Static BM driver.
  • 10.2mm Dynamic Driver.
  • Three sets of Tuning filters.
  • Eco-friendly Resin Shells.
  • Lozenge-Cut faceplates.
  • Leather earphone carrying case.
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Feels nice to see a different style of carrying case


  • Impedance: 18Ω@1kHz.
  • Sensitivity: 104dB±1dB.
  • Rated Power: 5mW.
  • Frequency Response: 20Hz-40kHz.
  • Weight: Approx 10g.
  • Termination: 3.5mm gold-plated plug.

Price: 79$

I would like to thank Hidizs for providing me with the review sample of Hidizs Mermaid MM2 (no affiliate link).

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I used Hidizs S9 Pro as my source, wide bore tips and balanced filters for my testing.

MM2 has no air vent on the shell as we see on many IEMs (mostly with dynamic drivers). It uses the three tuning filters instead. Each filter has different size holes (or different mesh with different holes) on them for the pressure ventilation which affects the sound character as “more, moderate or less bass”. Less bass filters are named treble filters as it feels like having more treble but in reality, the sound has less bass and less mid-bass.

Curiosity killed the cat, yes I also tried the MM2 without any filters and also closing the vent hole completely with tape. No go in both. The sound is completely muffled when taping. Even having a huge soundstage when no filter is attached, again the sound is on non-listening levels. So we understand that this tuning technique is a result of the good engineering of Hidizs.

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I personally quite enjoyed the bass performance on Hidizs MM2, it was engaging and full but still balanced with the rest of the sound. Maybe a little diffuse and smooth in its delivery of texture but overall, accurate and dynamic. The mid-bass has a cleaner sounding low-end, both in terms of note timbre and tone. Bass remains slightly warm and notes are a little thicker and more weighted and accurate. There remains a strong sub-bass drive and excellent extension with a tight, solid slam and rumble for engagement. Mid-bass is impressively articulate and bass hits hard at the very bottom.


Clean, clear and smooth, enhanced vocal definition in addition to a forward centre midrange that brings vocals to the fore. The smooth lower treble creates a similarly smooth articulation that saps any intensity or harshness from its forward midrange presentation. Hidizs MM2 compensates by slightly reducing the centre midrange hump and introducing a smoother upper-midrange. The midrange never comes across as blunted or veiled. Similarly, vocals sound almost as extended and the timbre is natural. The combination of cleanliness and clarity here is no small feat and the MM2 represents good tonality and timbre performance.


Hidizs MM2 has a clean treble response. Sounding generally smooth and linear. The MM2 has a sharp attack for clean and highly-defined sound. Decay is quick and note body is accurate. It has a good level of detail retrieval and micro-details. As the lower treble has been slightly smoothed off, this presentation isn’t too sharp nor is it too forward, though details still stand out clearly to the listener due to the style of note presentation. The MM2 sounds energetic and engaging. The MM2 is quite a smooth performer, engaging with its sharp and clean response.

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Hidizs MM2 has a good soundstage performance as you can expect from a semi-open design IEM, thanks to the replacement of the tuning filters. The imaging both in layers and of instruments is also very satisfying which makes the IEM a good technical performer in the whole picture.


Hidizs Mermaid MM2 brings effective “tuning filters” and a Dynamic Driver + Magneto-Static hybrid driver setup for less than 100$ on the market which results in a very fun experience both in sound and understanding one of the tuning techniques in IEMs. It’s always good to have a “working” option for easy tuning of your IEM. Feels like you get 3 in 1.