The THIEAUDIO Monarch MKIII are premium in-ear monitors (IEMs) positioned just below the Prestige LTD flagship IEMs in the company's current lineup. THIEAUDIO claims their revamped design for the Monarch MKIII means these buds produce a punchier sub-bass and louder output with lower distortion than their predecessor, the THIEAUDIO Monarch MKII. But have these IEMs done enough to reign over your ear canals? Read on to find out.
Our Verdict
The THIEAUDIO Monarch MKIII are good for neutral sound. Their bass response is elevated compared to our target, but not overly so. Kick drums sound thumpy, and basslines have enough punch and warmth to cut through without ever overpowering the mix. Vocals and instruments are rendered accurately and with detail, so your favorite singers will sound just like themselves. Their treble range is more inconsistent and dulls sounds like sibilants and cymbals a little. Nonetheless, they deliver audio with remarkable consistency, so once you get a good fit you'll get the same sound with each wear. Their passive soundstage isn't very immersive, and the sound feels as if it's coming from inside your head, but that's to be expected from in-ears.
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Remarkably consistent audio delivery.
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Stable fit.
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Poor passive soundstage.
The THIEAUDIO Monarch MKIII are a middling choice for commute and travel. They don't have active noise cancelling and, therefore, do a poor job of blocking out bassier sounds like the rumble of a plane engine. That said, they're able to passively block out a good amount of mid-range sounds like commuter chit-chat. They also leak very little audio, so anyone nearby won't be bothered by your audio. Their hard-shell carrying case is great for transporting the buds, but neither the buds nor the case have an IP rating, so be careful not to spill anything on them while in transit.
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Great mid- and treble-range noise isolation.
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Leak very little audio.
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No controls on the buds or cable.
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No IP rating against water or dust damage.
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Poor at blocking out bass-range sounds like engine rumble.
The THIEAUDIO Monarch MKIII are mediocre for sports and fitness use. On the plus side, they do a good job blocking out mid-range sounds like people talking in the gym, and they don't leak much sound, so anyone working out near you won't be bothered by your audio. On the other hand, they don't have any controls, so adjusting your music mid-step isn't easy, and they don't have an IP rating against water or dust damage, so these would be a poor choice for an outdoor run. And then there's the cable. While it's detachable, it's heavy and can easily catch on something, which could result in damage to the cable, connectors, or buds.
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Great mid- and treble-range noise isolation.
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Leak very little audio.
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No controls on the buds or cable.
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No IP rating against water or dust damage.
The THIEAUDIO Monarch MKIII are sub-par for office use. They don't have an integrated microphone, so you'll need a standalone mic to take calls. Some might also find their in-ear fit a little uncomfortable for long days at the office. On the other hand, they do a good job blocking out mid- and treble-range sounds like office chatter and the whine of a nearby fan.
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Great mid- and treble-range noise isolation.
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No integrated microphone.
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No controls on the buds or cable.
The THIEAUDIO Monarch MKIII are wired-only headphones; you can't use them wirelessly.
The THIEAUDIO Monarch MKIII are mediocre gaming headphones. They're comfortable enough for shorter sessions, but since they're IEMs, they don't have the plush ear pads that traditional gaming headphones have. You probably won't want to wear these for marathon sessions. They also don't have a microphone, so you'll need a standalone mic to chat with fellow players. That said, other than the poor passive soundstage, which is to be expected from in-ears, these do a great job reproducing everything from explosions to dialogue, and their excellent imaging means you can accurately locate objects like footsteps in the stereo field.
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Great mid- and treble-range noise isolation.
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No integrated microphone.
The THIEAUDIO Monarch MKIII don't have a microphone, so you'll have to bring your own mic if you want to use them for phone calls. If that's your plan, these do a good job blocking out the sounds like office chatter, so you can hear the person on the other end of the line.
- 7.6 Neutral Sound
- 5.8 Commute/Travel
- 6.1 Sports/Fitness
- 5.7 Office
- 4.1 Wireless Gaming
- 6.1 Wired Gaming
- 2.4 Phone Calls
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Updated Nov 22, 2024:
The following test groups have been updated after Test Bench 1.8: Sound Profile, Raw Frequency Response, Bass Profile: Target Compliance, Mid-Range Profile: Target Compliance, Treble Profile: Target Compliance, and Peaks/Dips. Text changes have also been made throughout the review and to the side-by-sides to match these results.
- Updated Nov 19, 2024: We've converted this review to Test Bench 1.8, which updates our target curve and Sound tests. You can read more about this in our changelog.
- Updated Sep 13, 2024: Review published.
- Updated Sep 10, 2024: Early access published.
- Updated Sep 04, 2024: Our testers have started testing this product.
- Updated Aug 26, 2024: The product has arrived in our lab, and our testers will start evaluating it soon.
- Updated Aug 07, 2024: We've purchased the product and are waiting for it to arrive in our lab.
Differences Between Sizes And Variants
The THIEAUDIO Monarch MKIII come in one variant, which has a black body and a black-and-white faceplate. However, if you're willing to pay a little more, you can order custom versions directly from the brand. Currently, they offer a total of six additional body colors and 14 faceplate styles for you to mix and match as you wish.
We expect our results to be valid for any of the customizable combinations on offer; see our model's label.
If you encounter another variant of these headphones, please let us know in the comments, and we'll update our review.
Compared To Other Headphones
The THIEAUDIO Monarch MKIII are premium in-ear monitors aimed at listeners who want portable high-fidelity audio reproduction. They share certain sonic characteristics with the MOONDROP x Crinacle DUSK, though the THIEAUDIO have a more detailed treble range. The MOONDROP x Crinacle come with a DSP cable, though, which gives you some scope for custom tuning. If you're looking for IEMs with a similar sound profile but can't stomach the THIEAUDIO's hefty price tag, the TRUTHEAR x Crinacle ZERO: RED are affordable IEMs that also have a warm sound.
If you want more high-quality sound headphones, check out our recommendations for the best audiophile headphones. You can also check out the best in-ear headphones and the best headphones for music.
The MOONDROP Blessing 3 and the THIEAUDIO Monarch MKIII are IEMs with slightly different sound profiles. The THIEAUDIO have a slightly elevated bass range that lends a touch of extra thump and punch to kick drums. They also have a slightly recessed treble, which either enhances their smooth sound or makes them feel a little dull, depending on your preferences. The MOONDROP are also significantly cheaper than the THIEAUDIO and deliver a less excited sound. They're also a little lighter and apply less pressure within the ear canal, so some users will find them more comfortable.
The TRUTHEAR x Crinacle ZERO: RED and the THIEAUDIO Monarch MKIII have similar sound profiles but very different prices. If you like a warmer, smoother sound, either of these pairs will suit you well. That said, the THIEAUDIO leak less audio and do a better job blocking out external noise, but they are significantly more expensive. Whether the improvements are worth the cost is up to you.
The MOONDROP x Crinacle DUSK and the THIEAUDIO Monarch MKIII are premium IEMs targeted at users looking for the very best sound reproduction. Both pairs have fairly similar sound profiles, offering plenty of thump and rumble in the low end, though the THIEAUDIO offer a more detailed treble range. Both pairs present instruments and vocals accurately. The THIEAUDIO are significantly more expensive than the MOONDROP and lack the MOONDROP's DSP cable, allowing you to apply EQ presets to your audio.
The THIEAUDIO Monarch MKIII and the TRUTHEAR x Crinacle ZERO are targeted at different segments of the IEM market. The THIEAUDIO are much more expensive than the TRUTHEAR but the two share a somewhat similar sound profile; with a prominent bass response and balanced mids. That said, the THIEAUDIO's treble response skews the overall frequency response towards sounding warm, while the TRUTHEAR have a brighter treble response. If you're a bright trap triplet hi-hats fan, you might find the THIEAUDIO too dull.
Test Results
The THIEAUDIO Monarch MK3 are premium IEMs. The buds' bodies are made from premium resin. We tested the stock colorway version, which is mostly black apart from a swirly white pattern and some colorful, glittery highlights on the outer face of each bud. The THIEAUDIO brand name is printed on each bud in pale grey lettering. You can also order the buds with custom colors and faceplates directly from THIEAUDIO.
The contoured buds are designed to sit securely in each concha, supported by a copper-colored cable that wraps over your ears. Text on the inside of each bud helps you distinguish between the left and right one. They come with three sets of translucent white silicone ear tips and three sets of black foam tips that are color-coded by size.
The THIEAUDIO Monarch MK3 have a decently comfortable fit. They come with small, medium, and large tips in both silicone and foam, so most people will have enough variety to find a fit and seal that works for them. However, if you've smaller ears, you might find that even the smallest tips are a bit painful. The outer part of the buds nuzzle easily and securely into your concha and distribute their own weight well. That said, they're quite heavy for IEMs, which may cause you some pain, and their heavy cable can create discomfort by pulling down on the buds.
The THIEAUDIO Monarch MK3 are very portable, like most in-ears. Still, it's worth noting that they're a bit heavier than many other IEMs.
The THIEAUDIO Monarch MK3 come with a zip-up hard-shell case to store the buds and their accessories. The case is covered in a sturdy-feeling, thick fabric, and it'll do a good job protecting the buds from everyday damage like drops. That said, it doesn't have an IP certification, so be careful not to pack the case next to anything that might leak liquid. The case is lined with softer material so that the buds don't get scratched. There's also a pouch on the inside, which helps keep the accessories organized, and an elastic band secures the buds in place.
The THIEAUDIO Monarch MK3 have a very good build quality. The bodies of the buds themselves are made from a high-quality resin that feels very robust, and the metal tips covering the speakers have a premium feel. Like many IEMs, the pins that connect the cable to the buds are very small and could get bent if not handled with care. Finally, the sturdy build quality of these headphones comes at the cost of added weight. The cable is heavy, and the buds weigh twice that of competitors like the MOONDROP Blessing 3.
These IEMs have a good, stable fit. They are designed to fit comfortably in your concha, and their cable then hooks over your ears, which helps keep them in place. Even heavy headbanging to your favorite Haken tune won't dislodge these from your ears. However, their cable is quite heavy, and if you move around a lot, the weight of it could cause them to become dislodged, breaking their seal with your ears. You'll also want to take care not to snag the cable on anything.
- THIEAUDIO Monarch MKIII headphones
- Detachable cable (47 in/1.2 m)
- 3x adapters (1/16 in/2.5 mm balanced, 1/8 in/3.5 mm single, and 11/64 in/4.4 mm balanced)
- 3x pairs of foam tips (S, M, L)
- 3x pairs of silicone tips (S, M, L)
- Hard-shell carrying case
- Microfiber rag
The THIEAUDIO Monarch MK3 have a well-balanced sound profile that is generally flat in the bass- and mid-ranges, before rolling off slightly in the treble range. That roll-off lends these IEMs a slightly warm, bass-heavy tonality, but they're never boomy or muddy. Kick drums feel thumpy, and the slight boost in the mid-bass ensures basslines have enough punch to cut through busy mixes. A peak in the low-treble can make vocals sound just a touch harsh at times, especially relative to the generally recessed treble range, but the overall sonic signature is more smooth than piercing.
The THIEAUDIO Monarch MK3 have outstanding frequency response consistency. In fact, they're among the best we've tested. Once you get a good fit and seal, these buds will deliver consistent audio with every wear.
The THIEAUDIO Monarch MK3 have amazing bass compliance. The whole bass range response is slightly emphasized compared to our bass range target, resulting in thudding kicks and basslines that don't overwhelm the mix. In songs like Bitter Melon by Cola, each note of the prominent melodic bassline is clear, and individual pitches don't jump out of the mix unnaturally.
The THIEAUDIO Monarch MK3 have excellent mid-range compliance with our target curve. The low-mids are virtually flat, but a small dip in the mid-mids can make instruments feel a touch distant. The high-mids are very slightly emphasized: vocals in songs like Send My Love (To Your New Lover) by Adele sound clear and detailed without being harsh.
The THIEAUDIO Monarch MK3 have good treble compliance with our target. If you like a warmer sound, these are a good choice because the entire treble range is de-emphasized. A slight dip in the low treble means that sounds like fingers plucking on nylon guitar strings lose a little detail and articulation. The entire mid-treble region is recessed, making cymbals sound dull and sibilants like S and T a little lispy.
The THIEAUDIO Monarch MK3 have excellent peaks and dips performance, meaning they do an amazing job of following their own sound profile. Most deviations are found in the treble range, where a peak in the low treble and a couple of small dips in the mid-treble mean vocals can sound either slightly harsh or dull, depending on the singer's pitch.
The THIEAUDIO Monarch MK3 have outstanding imaging, and although we've only tested one product by the manufacturer, these results suggest superb quality control and ergonomics. Our unit's drivers are well-matched in group delay, amplitude, frequency, and phase response, so objects like voices are accurately placed in the stereo field, and the soundstage doesn't feel unnaturally tilted to the left or right. There's a small peak in the mid-range phase response, but it's not audible. Keep in mind that imaging varies between units, so these results are valid only for our unit.
These IEMs have a bad passive soundstage performance, but that's to be expected from IEMs. Their in-ear design means audio can't interact with your outer ear like it can when you wear over-ears, meaning that they don't lend a sense of distance and width to the passive soundstage. Audio feels as though it's coming from inside your head and not two speakers in a room.
These IEMs have good weighted harmonic distortion performance. Most frequencies fall within good limits. Even the broad peak from the mid-mid to mid-treble won't be audible to most listeners. Overall, these IEMs reproduce audio purely and cleanly.
These are the settings used to test these headphones. Our results are only valid when used in this configuration.
These headphones have great full-range noise isolation, which they accomplish purely via passive isolation. Since they don't have ANC, they don't do a great job of blocking out bass-range sounds like the rumble of a bus engine. However, they do a very good job of isolating you from mid-range sounds like chatty coworkers and excel at blocking out trebly sounds like fan whine.
These IEMs do a decent job of blocking out everyday sounds. They won't isolate you from the low-pitched rumble of a plane engine or a passing bus, but they'll greatly reduce the ambient sounds of an office, from your colleague's voice call to A/C whine. You also won't hear much in the way of pedestrian chit-chat when out on the street.
The leakage performance is remarkable. Even if you listen at loud volumes, audio that does escape is concentrated in the low- and mid-bass regions and will sound muffled to anyone nearby. Feel free to blast your favorite Sunn O))) tunes without fear of bothering people around you.
These IEMS come with a 47-in/1.2-m detachable cable. The smaller two-pin connectors plug into the buds, and the four-pin connector plugs into one of three adaptors: 1/16 in (2.5 mm) balanced, 1/8 in (3.5 mm) single, or 11/64 in (4.4 mm) balanced. You don't need a dedicated amp to drive these.
These buds don't have a built-in microphone, so if you connect them to your PC, you'll only receive audio.
You can plug these into your PlayStation controller's AUX port, but they can only receive audio as they don't have a microphone.
You can receive audio from your Xbox by plugging these into an AUX port. They don't have a mic, so you'll need to add one if you plan to chat while you game.