ThieAudio, over a quick period seems to have built a solid fanbase. Usually, their works are tuned based on popular IEM entries or fanbase opinion and creating a solution for people running on a budget. Say what you want but giving the rapid growth of the company in just one year, I think so far it has worked quite well.
While I haven't heard some of their top product, I have once reviewed the ThieAudio Legacy 3 (and listened to the ThieAudio Voyager 3) and was quite unimpressed by them.

The ThieAudio Monarch is one of ThieAudio's latest entries along with the Clairvoyance (I know L5 exists now but give me a break). This time, the IEM's backstory itself is a bit interesting as it is a collaborative effort of ThieAudio with a member of the community. Hence, this piques my interest to the point of buying the IEM as well. Let's see how it performs.

Before going into the post, if you are new, please read this before having any comments regarding my writing or point of view‌.


The ThieAudio Monarch was purchased from Linsoul for this review.

Build and Accessories:

ThieAudio Monarch packaging
  • 3 pairs of foam eartips (S/M/L - I believe it is Tripowin Spiral Groove)
  • A pairs of Spinfit CP100 (Medium size)
  • Balanced 2.5mm 2-pin 0.78mm cable (ThieAudio EST)
  • Storage case
  • 2.5mm to 4.4mm adapters
  • 2.5m to 3.5mm adapters
  • The IEM itself  

The storage case of the ThieAudio Monarch is a fake brown leather case which is quite sturdy, although looks wide, but it is just enough to fit both the IEM and the cable into. Nonetheless, it is quite usable portability wise so I have no complaint.
The cable though, is where some people might have issues with. It's a sturdy cable with thick braiding and have metal enclosure on the Y-split, 2-pin connectors, L-shaped jack and even the chin slider. However, it is slightly heavy. The cable rubbed my ear quite often and causing some discomfort but it is not a big issue personally.

And here comes the big boi: In literal means the Monarch is quite big, combining with a sealed fit it has stretched my small ears a little bit. There is also one more issue with the Monarch builds is its short nozzle, as some ear tips have prone to stuck into my ears quite often. Either that or it would just fall out and never to be found.
Anyway, design wise the IEM has a pseudo-custom black shell with seashell-styled backplate (?), on top of the shell, there are 2 vent-hole with red/blue outer rings as side indicators. The backplate can be customized with an extra 60$ on Linsoul purchase page which is a bit expensive in my opinion but is still quite nice to have.


Overall impression:

This review will mainly based on the ThieAudio Monarch with Spinfit CP100 and Moondrop Starfield's stock eartips

I have been spending weeks, pulling my mediocre writing skill trying to start off this section without success so screw it, let's get thing straight here: The ThieAudio Monarch is good, in some case, excellent for me even!

ThieAudio Monarch frequency response - Taken from

Overall, the ThieAudio Monarch sound signature can be described as Neutral with bass boost. To be more specific, I would even regard the Monarch's sound presentation as Neutral with sub-bass focus due to how the bass region was tuned.

Speaking of sub-bass, it's excellent and it is one of the reasons why I would recommend this IEM for sub-bass lovers due to how satisfying it is. That being said, while the 150Hz boost keeps the bassline clean from bleeding into the mid-range, I sometimes find myself wanting a bit more punch for some of my electronic tracks.

And while I am at it, another interesting trait that I found from the Monarch is the linear response from 150Hz to 1kHz. This, combining with the cleanly boosted bass makes it a double-edged sword due to how the Monarch's sound is presented.
No doubt, Japanese female vocals are forward, treble extended quite well. But while this pattern gave the Monarch some clarity, the Monarch would end up being "dry" for some ears. That being said, comparing to something like the Etymotic ER4S which I found a bit overwhelming at times, the Monarch keeps this trait while still being deadly enjoyable for me. But again, the lack of warmth can be a detrimental factor for some people though: quite notable on instruments like Classical Guitar; heck, while this is not a big issue but even with Japanese vocals I found myself yearning for some more lower-mid boost sometimes.

The Monarch's imaging is quite competent as layers of instruments are presented quite well without congestion. Soundstage is above average for me though cannot compete with some of my favorite pieces of gears - maybe more depth and/or height might work? I would also want more mid-bass texture though but this is a small problem for me compared to what the Monarch has accomplished however.

It seems like being neutral, clean, and technical is what the Monarch is trying to accomplish here, I wonder how the other brother is?

Sound comparisons:

vs Moondrop S8:

Comparison graph was made by The Graph Comparison Tool

Comparing to the Moondrop S8. I personally feel like this is a win for the ThieAudio Monarch mostly due to the upper hand it have in terms of has response and treble extension.  

The S8's bass isn't bad by itself, but it is ultimately... still a BA bass. Not only that, Monarch nails the treble responses where Moondrop S8 just feels lacking in comparison.

That being said, the Moondrop S8 has some points for some people over the Monarch though, one of them is the tonality which is noticeably warmer than the Monarch. Vocals sound more forward on the S8 but might get a bit shouty for people who don't like Harman response.

Staging and Imaging wise, both of these IEMs are quite competent, however, the S8 fall slightly short in terms of instrumental positioning which is a bit smeared together. Details retrieval of both IEMs are quite comparable at this point but do note that the Monarch prioritize clarity which can be an important factor for someone making a purchase decision.

Solving the lower mid problem:

As Crinacle pointed out, the impedance curve of the Monarch is a downslope curve, and since some people in the Vietnamese community has been asking me for some info/impression on this to the point providing me some free resistors... Sure...

Comparison graph was made by The Graph Comparison Tool

Anyway, aside from the people who would want to boost the Monarch sub-bass to the fourth dimension, my personal reason if I would ever go for this method is that I would want more lower midrange boost - which would fix my only problem with this IEM.
And the result? I got what I want... by sacrificing 2 of the strong points of this IEM:

  1. The bass: While I can find the sub-bass quantity tolerable, it's actually have made the lackluster mid-bass to shows it ugly self, and this is just the 30 Ohm variant - The bass has gone to the point of being muddy with the 80 Ohm resistors
  2. The upper midrange/treble: This admittedly made the Monarch less energetic so some people finding the stock sounds harsh or too exciting can find this as a plus. But honestly, I don't like this, as instruments like cymbal now lacks some sparkles that I quite like.

Yeah no, this is a horrible idea. I decided to whip REW up and try to put a small equalization filter with my iBasso DX160 instead.

ThieAudio Monarch predicted equalization - Note the SPL scaling
Filter  1: ON  PK       Fc   150.0 Hz  Gain   3.30 dB  Q  0.400
Preamp: -4 dB (Not necessary if you use DX160 due to the pre-applied gain)

Despite the mid-bass bluntness showing off a bit, I found it is an ok compromise to make. This equalization has been my go to daily choice for a while so despite all of the pitchforks of some obsessive purists, I gonna keep this.

Edit: Some people mentioned the fact that my EQ accidentally looked Clair-like which I didn't aware so I might have discovered a way to turn a Monarch into a Clair here... I might want to listen to the Clair for confirmation...


Given my impression up there, my rating for the Monarch is already quite obvious. While it's definitely not on the top of my list, I personally can see it comes pretty close. For someone who are looking for a neutral, technical sound presentation but with some extra "spices" to prevent it from overly boring, Monarch would highly fit the bill.

Bravo ThieAudio for their successful community collab! Now, I hope that they would actually make some improvement for their lower-tier products.

Recommendation Rating: Recommended

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