THIEAUDIO Monarch MKIII Review featured image


Our in-depth review of the THIEAUDIO Monarch MKIII, which is a 3rd generation hybrid 10-driver universal IEM featuring IMPACT2 technology. It is priced at $999.

Disclaimer: This is a sample in exchange for our honest opinion. Headfonics is an independent website that does not have any affiliate links or status. We thank Linsoul for this opportunity.

To read more about Thieaudio products we have previously covered on Headfonics please click here.

Note, that this article follows our latest scoring guidelines which you can read here.

THIEAUDIO Monarch MKIII Review featured image
The THIEAUDIO Monarch MKIII is an excellent 'tribrid' multi-driver IEM. You get excellent power, clear vocal performances, and a very resolving staging performance in a relatively comfortable customizable shell with a cable that caters to the most popular connector outputs.
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Dynamic and exciting sound signature
Excellent imaging
Multiple Cable connector options
Larger than average IEM shell dimensions for a universal
Slightly bland stock shell design
Reader's Score

We have covered a lot of THIEAUDIO IEMs and headphones over the last few years such as the Oracle MKII and the Elixir to name but a few. Weirdly, we have missed what many consider to be one of their best offerings to date, the hybrid Monarch Series.

Well, that changes today, with our THIEAUDIO Monarch MKIII review, and as a bonus, we have acquired a Monarch MKII to compare against within our selected comparison section on page 3. 

I also presumed MKIII would replace MKII but that does not seem to be the case with Linsoul, their main backer, still selling both at the same price of $999 on their website.

That might create a bit of a dilemma for would-be first-time owners of this multi-hybrid IEM because while both honestly sound ridiculously good for their price point they do offer different sound signatures.


Tech Highlights

The THIEAUDIO Monarch MKIII is a ‘tribrid’ multi-driver universal IEM and is positioned just below its Prestige Ltd flagship monitor in the company’s current lineup. Each shell uses 10 drivers with a mixture of dynamic, balanced armature, and electrostatic. 

The precise grouping includes two 10mm composite diaphragm dynamic drivers for the lows, 6 BA for the mids and highs, and 2 EST drivers for the ultra-highs with a 4-way passive crossover.

Both the balanced armature and electrostatic drivers are dual driver modules plucked from Knowles, (DWFK 31785), and Sonion, (Sonion 28UAP01 for the mids BA) which is consistent with the previous Monarch MKII.

What has changed with the Monarch MKIII is the use of two 10mm dynamic drivers instead of 1 as well as being configured into a push-pull isobaric configuration.

THIEAUDIO has coined this implementation as IMPACT2 to improve not only the presence and impact of the lows over the previous Monarch but also improve the perceived textural detail from the lows without any clipping and distortion.

The Monarch MKIII has a reasonably low impedance rating of 18Ω but on paper at least it seems somewhat inefficient at 99dB @ 1kHz (+/- 1dB). You can find out how it performs with sources and dongles in more detail on page 2 of this review.

THIEAUDIO Monarch MKIII front faceplates


The Monarch MKIII is a 3-piece build comprising of a customizable faceplate, a polished black medical-grade resin shell with recessed 2-pin 0.78mm sockets which is also customizable, and a stainless steel spout. 

The ability to customize is provided at the checkout for an additional $100 on the base price. There is provision for up to 15 different faceplate designs as well as 6 shell options including the default black shell which is the version you are seeing in our review sample pictures. 

The default plate is a mix of reflective pink glitter sprinkled over some background white swirl over roughly half of a matte black background. It’s a professional if somewhat slightly understated design though with the ability to customize you bring plenty of ‘eye candy’ to your particular version.

The Monarch MKIII form factor with that additional dynamic driver is more to the chunky side for a universal IEM and certainly a bit deeper than the MKII.

Mind you, that sizing description is contextual. If you are coming from something like the Noble Audio Ronin it is a fair bit smaller and the contouring is aggressive enough to slip easily in your ear and stay in place. 

THIEAUDIO Monarch MKIII comfort or side view

Comfort & Isolation

Unless you have very odd-shaped ear canals the Monarch MKII should not give you any issues in terms of getting a comfortable fit.

Surprisingly, despite it being larger than the MKII, the Monarch MKIII felt more secure in my ear compared to the slimmer previous generation model. And, if you look closely at the two shells side by side you will see the MKIII has more aggressive contouring on the underside compared to the MKII which seems to give it a bit more grip in the concha basin.

The level of isolation is slightly above average for a hybrid but nothing to write home about and more or less the same level as the MKII.

Both the old generation and Monarch MKIIL come with the same selection of tips and both are vented hybrids so there is a more passive noise creeping in from the likes of an aircon than an all-BA design.

Just to note, the venting port on the Monarch MKIII is not at the front of the main shell rather than the back which I presume is to prevent the vent from being blocked by the back of your ear combined with the new isobaric venting chamber’s design.


You get two sets of tips with the Monarch MKIII, one set is a single flange wide bore white silicone and the other set is foam and both come in small, medium, and large sizes.

The foam tips isolate a bit better but at the cost of some additional pressure in the ear canals. The silicone tips provide a more comfortable fit for longer listening sessions and generally provide a more open sound signature.

THIEAUDIO Monarch MKIII cable connectors

Stock Cable

THIEAUDIO has retained the innovative interchangeable triple plug system from the MKII but this time the Monarch MKIII stock cable and barrels get a bit of an upgrade. 

Gone is the older 26AWG Litz copper from the old cable and now we have a 1.2 meter 22AWG 6N OCC Silver-Plated and Graphene Silver-Plated wire. The outer has also changed significantly with a twisted-finish PVC jacket rather than the braided nylon jacket alternative from the MKII cable. 

The barrels have also been upgraded to a thinner diameter all-black aluminum barrel that shaves a bit of weight off the older fatter carbon printed designs from the MKII.

The net result is a cable that feels lighter in the hand and a bit more plug-friendly for smaller portable amps that might have their sockets fairly close together. Especially the 2.5mm TRRS socket choice which always felt a bit too big for me with iBasso amp cards.

With the nylon jacket gone, the new Monarch MKIII stock cable also suffers less from microphonics on handling compared to the MKII cable.

THIEAUDIO Monarch MKIII accessories

Packaging & Accessories

Aside from an upgraded THIEAUDIO brand label on the outside, the Monarch MKIII package is more of the same as the last generation. And that is perfectly fine because it is professionally packaged albeit nothing with what you might call the ‘wow factor’.

You get a box dimension similar to the new 64 Audio monitor packages with decent foam protection on the inside and the IEMs with the cable on display on the inside above the carry case. There are no additional layers underneath and all the accessories are neatly tucked away inside the case.

Even the case is the same though I have to say it seems a slightly darker shade of grey for the nylon compared to my older MKII case though time and the elements may have caused that.

The stiff framed case is reasonably large with a nice, rubberized zip for easy grip and plenty of space on the inside to fit your cable, monitors, and accessories which include a 4.4mm, 2.5mm, and 3.5mm plug for the stock cable connector system. I suspect you could fit a few additional IEMs in there also.

You should also expect to find the two sets of ear tips and a cleaning cloth all in their protective bags inside the carry case alongside the jacks.

Click on page 2 below for our sound impressions and recommended pairings.

Click on page 3 below for our selected comparisons.

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