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HZSOUND Heart Mirror Pro

HZSOUND Heart Mirror Pro


Bass Rich Heart of Mirrors


  • At the point of this article, my Heart Mirror Pro (HM Pro) has undergone over 150 hours of burn in and approximately 60 hours of actual listening
  • I don't do measurements, I just describe what I hear, from my own POV
  • I don't use EQ
  • The entirety of my impressions was done with stock HM Pro Foam Tips
  • Ultimately, my reviews are purely subjective and biased to my personal preference in sound

Hot on the trail of the highly regarded Heart Mirror, HZSOUND has rebooted the same offering with some tweaks intended to cater for diversified needs of the portable audio enthusiasts. Practically HM Pro, at least from the design and outer appearance remained the same as the OG HM.

The Build

Very Impressive! That’s my first reaction when I first unboxed my HM Pro. I don’t think anything within this price point can compete with HM Pro when it comes to build, package and accessories.

The IEM housing itself is a thing of beauty with mirror smooth Electroplated Zinc-alloy imparting elegance and grace. Housed within is a pair of 10mm CNT diaphragm dynamic driver, employing powerful N52 magnetic architecture, with Japanese DAIKOKU CCAW Voice Coil. Rated at 32 Ohm of Impedance with 110 dB of sensitivity.

Then there’s the beautifully crafted modular high-purity OFC silver-plated copper cable. The cable itself with simple twist braid and very pliable to the touch. The highlight being modular to allow for swapping of all three popular sizes for 2.5mm BAL, 4.4mm BAL and 3.5mm SE. The cable construction really felt very premium and equally graceful to match the IEM itself.

Even more impressive is the inclusion of dedicated separate cable which has proper inline MIC to be used with mobile phones directly or for usage of conferencing when attached to PC/Laptops. I have not seen anything like this before with other IEMs, especially not at this price point.

It does not end there. HM Pro comes with full range of tips to suit different preferences. I am happy so see the inclusion of foam tips on top of the regular three type of silicone units. HM Pro also comes with nozzle filters for further tuning (to dampen some high frequency if needed).

Last but not least, HM Pro also include very practical black case. Together with cable hook which can be used to manage the cable when on the move. I must say that on packaging alone HM Pro is a real winner.


Equipment Used

  • Xiaomi Mi 9T (3.5mm SE and USB Port)
  • Sony Xperia X Compact (3.5mm SE and USB Port)
  • Windows 10 with Native USB Drivers
  • HiBy Audio Player USB Exclusive Mode with FLAC files
  • CEntrance DACport HD
  • Cayin RU6
  • Ovidius B1
  • VE Abigail 4.4
  • NotByVE Avani
  • VE Megatron
  • MUSE HiFi M1
  • MUSE HiFi M3

Sound Impressions

Right off the bat, HM Pro exhibited traditional strong Harman-ish V curve profile – notable elevation of high frequencies and pronounced boosting of lower registers. The Midrange seemingly stepped back as how it is normally done with V sounding gears.

Timbral and tonal balance being organic yet very sparkly. The sort of characteristics to be expected of well-tuned traditional dynamic drivers.

The Midrange of HM Pro, albeit being stepped back (position wise), does offer rich and audible body. It does not sound recessed. Just that the staging are less forward. The Mids being smooth and realistic. I did not sense any attempt to add warmth or element of dryness to the presentation. Attack and decays of instruments being smooth edged with ample resolution.

However vocals wise. I observed that HM Pro may at times appear slightly peaky when subjected to some Soprano type. Alison Krauss for example, her peaky and boyish singing may appear borderline sibilant especially on crescendo sections, where she will pushed her singing to the max. On the same note, it would behave similarly with the vocals from Varg Vickerness (who wails all the time). Otherwise, the singing of Diana Krall (contralto), Sinne Eeg (contralto), Nick Cave (baritone) and Morrissey (baritone) appeared natural sounding. It is rich with proper depth and texture.

BASS, now this is where HM Pro differs significantly from the OG HM. Right out of the box I was shocked out of my wits with the amount of Bass this thing produced. It was literally a Bass cannon that overwhelms everything. However, despite all that, HM Pro Bass settled down more sensibly after 12 hours of Burn-In. After the first 20 minutes of initial use, I set it aside to burn with Pink Noise on loop. True enough 12 hours later I can clearly hear the Bass has stabilized and no longer sounding overly dominant. It gets better as more time allocated for aging. Now at approx. 150 hours, HM Pro has some of the most dense and deep Bass I have heard within this price range.

Midbass being impactful and commanding, yet manage to behave to not overwhelm everything else around it. Subbass deep and well extended. It is still a lot stronger than what I would prefer (in fact I prefer the OG HM Bass responses). But I can understand the trend nowadays seems to favor Bass heavy presentation and as such HM Pro came forth to cater for that needs.


Bass responses of HM Pro reminded me a lot to the sort of Bass performances from KOSS PortaPro. As I said earlier, it is authorative, impactful with slam and reverbs. Absolutely suitable for listening to electronic, dance, pop or fusion music. But may prove a bit over the top for Jazz, Folk, Bluegrass or Instrumentals.

However I must note that despite the richness in density, I feel that the Bass in general lacked a bit of details and texture. This perhaps due to focus on smoothness with Bass transients which masked the micro details. On the other hand it does offer good decays imparting smooth dispersal with vibrant seismic responses.

Switching to higher frequencies, I would say that HM Pro is a tamed version of the original HM. For those who are familiar with the OG HM, Treble brightness, shimmer and sparkle is what makes it special. OG HM was a thoroughbred Trebleheads IEM. Now with HM Pro, the upper frequencies has been re-tuned to be a bit more sensible and less metallic. It still has that airy Treble transients like the OG HM, but the level of shimmer and sparkle are reined in just enough to keep it exciting still. Which also means HM Pro is less euphonic as the OG HM. The energy and attack markedly more mature and well controlled. Treble decays however remained the same as the OG HM – so this is a plus in my book.


Perhaps one of the caveats that proved worrisome from my perspective, HM Pro appeared to struggle with speed and resolution – when subjected to handling of past paced music that contain lots of layers. This is evident when I use my HM Pro for Rock/Metal/Indie playlist. While it does not succumbed outright to being muddy, the soundscape seems to caved in and thus imparting cramped fuzzy lines between layers. Thankfully it fares better when playing most other music genre like Jazz, Pop, Folk or anything else that does not exceed 100 BPM.

Nonetheless, I would say the technical prowess of HM Pro is average at best. Imaging amply clean but not as clinical due to edge smoothing. The overall resolution proved enough for casual use.

Another element that I find to be less appealing would be the projection of spatial positioning. HM Pro exhibited traditional Left/Right split, which is common for most dynamic drivers. This means that HM Pro is not suitable for gaming or movie usage. HM Pro simply lacked holographic imaging.


One key element that HM Pro does better from the OG HM, it is a lot more efficient to drive. In fact I was pleasantly surprised to hear my HM Pro sounding so good with my weak Sony Xperia X Compact (which is under 1 Vrms). Further tests indicated that the efficiency of HM Pro goes to peak at around 2 Vrms, of which it sounded the best when powered by Cayin RU6 and Ovidius B1. Pushing it further with CEntrance DACport HD or VE Megatron at over 4 Vrms, I frankly can’t hear any difference in terms of fidelity which was already present with RU6/B1.

Final Words

In summary, I would regard HZSOUND Heart Mirror Pro as a solid performer for the asking price at just $80. Despite being Bass heavy as compared to the OG HM, HM Pro proved to be a more balanced sounding unit which will appeal to many. It is vibrant, fun and smooth. Some deficiencies with technical aspect but it is not a deal breaker really – for as long as HM Pro is not used to listen to highly pacey music.

Not forgetting how premium the whole packaging is, I believe HZSOUND should be made as example how manufacturers should package their IEMs. That modular cable alone is more than worth the price.

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