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?
Our Verdict
The THIEAUDIO Monarch MK3 are okay 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.
- Leak very little audio.
- Stable fit.
- No controls on the buds or cable.
- No IP rating against water or dust damage.
The THIEAUDIO Monarch MK3 are a good choice for commuting and travel. While they don't have active noise cancelling and don't block out much bassy engine rumble, they can passively attenuate a good amount of mid-range noise like commuter chit-chat. They also leak very little audio, so your audio won't bother anyone nearby. 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.
- Great mid- and treble-range noise isolation.
- Leak very little audio.
- Poor at blocking out bass-range sounds like engine rumble.
The THIEAUDIO Monarch MK3 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.
- Great mid- and treble-range noise isolation.
- Leak very little audio.
- No integrated microphone.
- No controls on the buds or cable.
- Poor at blocking out bass-range sounds like engine rumble.
The THIEAUDIO Monarch MK3 are wired-only headphones; you can't use them wirelessly.
The THIEAUDIO Monarch MK3 are mediocre all-in-one gaming headphones because they don't have a built-in mic, so you'll need to bring your own if you want to chat with fellow players. 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. That said, these do an excellent job reproducing everything from explosions to dialogue, and their remarkably well-matched left and right drivers ensure you can accurately locate objects like footsteps in the stereo field.
- Remarkably consistent audio delivery.
- Stable fit.
- No integrated microphone.
- No controls on the buds or cable.
The THIEAUDIO Monarch MK3 have great audio reproduction accuracy. Their frequency response barely deviates from their warm sound profile and have remarkably well-matched left and right drivers, ensuring accurate reproduction of objects in the stereo field. They also reproduce your audio without audible harmonic distortion, even at louder listening levels.
The THIEAUDIO Monarch MKIII have very good noise isolation performance, which is fairly noteworthy as they don't have active noise cancelling. Their passive isolation does a good job blocking out mid-range sounds like people talking, but you'll hear bassier sounds like a train's engine rumble.
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 sounds like office chatter, so you can hear the person on the other end of the line.
The THIEAUDIO Monarch MK3 have fantastic frequency response consistency. As long as you seat them properly in your ears, you'll get consistent audio with every wear.
Performance Usages
Changelog
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Updated Mar 12, 2026:
This review has been updated to Test Bench 2.1, which removes the Group Delay test and rebalances scoring for the Harmonic Distortion test and Audio Reproduction Accuracy performance usage. For more details, consult our full changelog.
- Updated Mar 12, 2026: This review has been updated to Test Bench 2.1, which removes the Group Delay test, and rebalances scoring for the Harmonic Distortion test and Audio Reproduction Accuracy performance usage. For more details, consult our full changelog.
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Updated Nov 18, 2025:
The Wired box has been updated to mention the CrinEar Daybreak.
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Updated Jul 29, 2025:
We've updated the Sound Profile box with a link to a downloadable folder of EQ settings that will help you match these headphones' frequency response to different target curves available in our Graph Tool.
Check Price
Differences Between Sizes And Variants
The THIEAUDIO Monarch MK3 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.
Popular Headphones Comparisons
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 more elevated bass range that lends 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. On the other hand, the MOONDROP are significantly cheaper and deliver a more balanced treble, which gives sounds like cymbals more shine than the THIEAUDIO manages. The MOONDROP are 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 balanced 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 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.
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 present low-treble range, which can help make vocals sound a little clearer in dense mixes. But both pairs present instruments and vocals accurately. But the THIEAUDIO are significantly more expensive than the MOONDROP and lack the MOONDROP's DSP cable, which allows you to apply EQ presets to your audio.
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You can also discover how we produce recommendations like this one so that you can find the best headphones (or earbuds!) for your needs.
Test Results
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