Thieaudio Monarch Review - Cut and Dry

Thieaudio Monarch Review - Cut and Dry

Yup, here’s another hype train that’s long since left the station. Sigh. Better late than never though, I suppose. Thieaudio took the IEM world by a storm last year with the release of two tribrid IEMs, the Monarch and Clairvoyance, and even now Thieaudio is reeling, struggling to catch up with the unprecedented demand. I’m sure you’ve already read a few reviews about this IEM, so I don’t mind spoiling it now: The Monarch is really good. In what appears to be a growing trend, it was tuned using the input of an IEM community member, and the results speak for themselves. Still, rest assured I won’t be pulling any punches in my assessment, so follow along as I break down the nitty-gritty of one of last year’s most hyped IEMs.

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Source and Drivability

All critical listening was done off of an iBasso DX160 (volume ~20) and A&K SP1000M with lossless FLAC files. The Monarch requires a bit more power to drive than most IEMs. This is because the Sonion electret drivers inherently require more juice, and correct implementation requires dampening the other drivers in the IEM. Still, I had no trouble running it off of an iPhone with the Apple dongle or the aforementioned DAPs, and I experienced no hissing. 

Thieaudio Monarch Accessories |

The Tangibles

The Monarch arrives in a discrete, green cardboard box. Inside you’re greeted by a waxed paper emblazoned with Thieaudio’s logo. The following accessories are included: 

  • Faux leather case
  • Medium SpinFit silicon tips 
  • s/m/l Tripowin Spiral Groove foam tips
  • 0.78mm cable terminated with 2.5mm jack
  • 2.5 to 4.4mm adapter, 2.5 to 3.5mm adapter

The cable itself is of good quality sporting full-metal hardware, but unfortunately, the adapter jacks leave something to be desired. They’re completely straight, quite long, and using them will significantly elongate the length of the jack making for some awkward pairings (images NFSW). I really would like to have seen L-shaped adapters included instead. Of course, none of this is an issue if you’re just going to use the stock 2.5mm jack. 

Thieaudio Monarch Review |

The Monarch itself is on the larger side of things, so smaller ears beware. That’s just how it works when this many drivers (1DD/6BA/2EST) are being crammed into an IEM! The overall build quality is quite good with no surface inconsistencies to the finish or the seam where the acrylic shell and faceplate meet. Speaking of which, the faceplate is beautiful. It’s not quite my thing, but it looks way better than I was expecting given the images shown on the Monarch’s product page. Connector pins are flush, 2-pin 0.78mm and there is a metal grill at the IEM’s nozzle. 

Sound Analysis 

Frequency response measured off of an IEC-711 coupler. There is a resonance peak at 8kHz, so measurements after this point should not be considered accurate. 

Thieaudio Monarch Frequency Response |

On paper, the tonality of the Monarch can be classified as “neutral with sub-bass boost”. It exhibits an incisive sub-bass shelf, a leaner midrange, and fairly linear, extended treble. The end-result is a clean, if not very “segmented” presentation in which there are clear delineations between each frequency band. 

Bass is almost exclusively sub-bass, leveling off just after 100hZ, tight and controlled. From a tuning perspective? Awesome. The only issue that comes to mind is if your music doesn’t quite token those super low frequencies. Still, y’all know that I'm a stickler for the intangibles just as much as I am the tuning when it comes to my bass. And unfortunately, the Monarch’s bass is more middling in this regard. I don’t find it particularly lacking in texture; however, hits are articulated with a certain limpness to them in stark contrast to the incisive bass shelf. Even the 64 Audio U12t - a strictly BA IEM, mind you - has better tacility, dynamic slam than this down low in direct A/B comparison. If we split the difference, the Monarch’s bass is decent, but far from being great. 

The midrange of the Monarch is characterized by a level trough from 200hZ-1kHz then a rise in the upper-midrange from 2-5kHz, resulting in what I’ve begun simply deeming as a “lean and mean” presentation. In this regard, the Monarch’s midrange is practically devoid of coloration, leaning slightly brighter and exhibiting abundant macro-detail. I’m almost reminded of the Empire Ears Odin in some respects, and indeed, the Monarch’s resolution is on par with some of the best in the game. Mind you, those are not words I sling lightly, and it’s high praise considering the Monarch clocks in at a fraction of the cost. 

Moving into the treble, I hear what sounds about equal parts impact and crash. Transient attack is well-defined, largely devoid of the characteristic “wispiness” that so many EST setups exhibit. Roll-off begins post-10kHz, sloping fairly linearly to around 18kHz, after which it dips strongly and exits the limits of my hearing. While I do think the Monarch would benefit from some more air up top accordingly, make no mistake: This is treble done correctly, and I think most would be hard-pressed to complain. 

The Monarch’s imaging is slightly above average. Incisiveness is excellent when it comes to left-right panning and positioning. The center image, however, takes on a more in-head quality with the Monarch struggling to re-create soundstage height and depth. Needless to say the result is a more 2-dimensional presentation (which is unfortunate given the impressive width) rather than one that completely envelopes the listener in a holographic bubble of sorts. 

Thieaudio Monarch Review |

Unforgiving Explication

A.K.A. I moan and groan about why the IEM in question fails to meet my high standards, and the section of this review you’ll want to skip if this type of more critical talk offends you. But you’re not going to, right? ‘Cuz this is the juicy, fun stuff. 

Subjectively, I have a lot more bones to pick, and here, we come back to the midrange. I can’t help but feel that tonal coherence is lacking; there is a fundamental disconnect between the scooped lower-mids and the more elevated upper-mids. The opening guitar strings of Keith Urban’s “Kiss A Girl” are thin, feel they’re being plucked half-heartedly, and the violin work on Emiri Miyamoto’s “Amour” album sounds unnaturally strained, at times borderline honky on more lively passages. On a more intangible level, BA timbre is most definitely present, and while the Monarch’s midrange only exhibits grain in moderation, it’s toeing the line with soprano-oriented stuff, including a lot of the test tracks from Taeyeon I use. Perhaps just over my line, and the result is an overly dry, sterile presentation which I can’t bring myself to outright hate, but that I also can’t completely agree with. And don’t get me wrong, the Monarch’s been well-tuned in the most “objective” sense possible.

This nagging apprehension grows as I scrutinize the Monarch’s intangibles more closely. The Monarch’s technical performance seems largely predicated on its macro detail. Even then, macrodynamic ability is heavily lacking; swings are caught somewhere in the middle to slightly upwards-skewed, exacerbating the overly dry presentation. This is not unlike the Empire Ears Odin, but the Odin had a level of intangible coherency and detail retrieval to pull it off with which the Monarch simply lacks. Without getting crazy in-depth, we circle back to my comments on the “segmented” tonality. I’m inclined to say that a good number of the Monarch’s coherency issues are baked into the tuning which, in turn, is inherently responsible for its strong technical display - namely, sheer resolution. You see where I’m going; there is a sort of self-destructive cycle at play between the Monarch’s tuning and intangibles. Suffice it to say that the Monarch is short more than a few cards of being a top-tier IEM. To be clear, I need stress that it is a terrific IEM for its respective price point. There is, however, a noticeable gap between the Monarch and the truly top-tier stuff in this reviewer’s opinion.

Select Comparisons

DUNU SA6 - $550

I’d liken the SA6 to being “the” $550 IEM, much like the Monarch is “the” $730 IEM. Both have been tuned very well and have the technical chops to be some of the most solid contenders in their respective price brackets. The SA6 follows a more traditional, U-shaped tuning with a dip in the lower-treble to prevent sibilance. It’s a warmer, smoother listen by comparison as a result. The Monarch takes a lead in technicalities with notably better resolution and positional cues; however, struggles like the SA6 with depth and soundstage height. 

Moondrop S8 - $700 

Honestly, this is probably the IEM I’d personally buy if I had $700, and I think it’s one of the Monarch’s few competitors. The S8 adheres closely to the Harman target curve, adding a tad more presence back to the lower-midrange and some more upper-midrange. It’s a little leaner in the notes perhaps, and likewise fairly dry, but not to the extent of the Monarch. I do find the midrange somewhat cleaner in the decay with less grain. You lose some of the timbre benefits of the Monarch’s DD, while the treble on the S8 is superbly extended, noticeably more than on the Monarch. Technicalities are about par between the two IEMs; however, the S8 takes the cake in coherency. Needless to say, these two IEMs are very different flavors. Like big sub-bass and max clarity? Go for the Monarch. Prioritize coherency and treble extension? Or enjoy weeb tuning? You’re going to want the S8. 

Unique Melody MEST - $1400

Whereas the Monarch has taken a clean, calculated approach to tuning, the MEST goes for a more unconventional, W-shaped tuning which I think will appeal to those who want more spice to their sound. Along these lines, the MEST also makes use of the EST drivers, but is more lower-treble oriented. On a technical level, the MEST is one of the few IEMs that approaches truly holographic levels of imaging and it exhibits excellent layering. Resolution is also a small step ahead of the Monarch, particularly in the midrange, where decay is a good deal cleaner. Like the Monarch, the MEST falters in coherence, but from a more intangible point standpoint. I’m inclined to say the MEST is the “better” IEM overall; however, it’s important to remember that it’s almost twice the cost and presents a very different flavor of sound. 

Thieaudio Monarch Review |

The Verdict

Needless to say I’ve been assessing the Monarch to standards with which many, much more expensive IEMs have kneeled. But a monarch does not kneel. And do forgive the theatrics, but just as a king would command one’s respect - irrespective of a clash of opinion - I am obligated to recognize the Monarch’s impressive sonic prowess. For $730, the Monarch is a game changer: One of the best tribrid IEMs on the market by virtue of how well-rounded it is, one of the best IEMs bar none in its price bracket. Sure, it helps that competition in this bracket is sparse, and it’s still a pretty dry sounding IEM overall. But the Monarch’s also a cut and dry, straightforward recommendation in the most positive sense, an IEM that (mostly) lives up to its moniker and that warrants a solid thumbs-up from this reviewer. 

Reference Tracks

  • Aimer - Hakuchuumu
  • David Nail - Let It Rain
  • Dreamcatcher - Silent Night
  • Illenium & Excision - Gold
  • Girls’ Generation - Galaxy Supernova
  • Joe Nichols - Sunny and 75
  • Keith Urban - Defying Gravity (2009)
  • Sabai - Million Days
  • Sawano Hiroyuki - Best of Vocal Works Remastered (2020)
  • Taeyeon - My Voice (2017)
  • Tiffany - I Just Wanna Dance
  • Tom Day - Where Were We

This unit was kindly provided for review by Linsoul.


For an additional perspective, check out Resolve's review of the Thieaudio Monarch:

Buy the Thieaudio Monarch at for the best available price.

Discuss the Thieaudio Monarch on the HEADPHONE Community Forum.


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