Short answer: the ThieAudio Monarch MKII. It ranks #46 of 297 in-ear headphones by sound quality (rated 4.6/5); the ThieAudio Monarch MKIV ranks #98 (rated 4.4/5).
The case for the ThieAudio Monarch MKII: A preference score of 81 from crinacle’s measurement and just 1.45 dB of deviation make it one of the most accurate in-ears available. The tradeoff: Those measurements show a 5.6 dB dip near 6.5 kHz and treble about 2.6 dB below target, which softens cymbal attack slightly.
The case for the ThieAudio Monarch MKIV: Across 14 squig.link measurements it posts a preference score of 79.0 with a very smooth 1.31 dB spread. The catch: Presence sits 2.7 dB below target with a 3.7 dB dip near 6.4 kHz, so vocals and strings lose some immediacy.
Buy the ThieAudio Monarch MKII. It is rated higher for sound quality than the ThieAudio Monarch MKIV.
Looking for alternatives? See the complete Headphones rankings.
Specifications Side By Side
| ThieAudio Monarch MKII | ThieAudio Monarch MKIV | |
|---|---|---|
| Price | - | $1,149.00 |
| Ranked | #46 of 297 in In-Ear Headphones | #98 of 297 in In-Ear Headphones |
| Form Factor | In-ear | In-ear |
| Back | Closed | Closed |
| Harman Preference Score | 81 (measured by crinacle, via AutoEQ) | 79 (median of 14 squig.link measurements, calibrated to AutoEQ) |
| Deviation From Target | 1.45 dB standard deviation | 1.31 dB standard deviation |
| Tonal Tilt | -0.22 (negative is warmer, positive brighter) | -0.43 (negative is warmer, positive brighter) |
| Connection | Wired | Wired |
| Driver Type | Hybrid (1 dynamic + 6 balanced armature + 2 electrostatic) | Hybrid (2 dynamic + 6 balanced armature + 2 electrostatic) |
| Drivers | 1 x 10mm dynamic + 6 x balanced armature + 2 x electrostatic | 2 x 8mm dynamic + 6 x balanced armature + 2 x electrostatic |
| Impedance | 36 ohms | - |
| Sensitivity | 108 dB/mW | 100 dB |
| Frequency Response | 20Hz - 20kHz (Manufacturer specified) | 10Hz - 44kHz (Manufacturer specified) |
| Sub-bass Extension | Within 6 dB of target down to 20 Hz (-0.3 dB at 30 Hz) | Within 6 dB of target down to 20 Hz (-0.2 dB at 30 Hz) |
| Built-in Microphone | - | No |
Related Headphone Comparisons
More worthwhile head-to-heads for ThieAudio Monarch MKII:
- ThieAudio Monarch MKII vs ThieAudio Monarch MKIII
- ThieAudio Monarch MKIII vs ThieAudio Monarch MKIV
- Shuoer Cadenza 12 vs Shuoer Cadenza 4
- EPZ G20 vs EPZ G30
- EPZ G10 vs EPZ G30
Prices on this page were last checked October 10, 2026 at 5:37 PM UTC. Product prices and availability are accurate as of that date/time and are subject to change; the price and availability shown on Amazon at the time of purchase will apply to the purchase of this product.
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The Two Headphones In Full
ThieAudio Monarch MKII AliExpress eBay
Pros: A preference score of 81 from crinacle’s measurement and just 1.45 dB of deviation make it one of the most accurate in-ears available. Across 19 hobbyist measurements on squig.link, sub-bass and bass sit within half a dB of target down to 20 Hz, so kick drums and synth bass have full, tight weight. Its 108 dB/mW sensitivity and 36 ohm impedance mean a phone drives it easily, and the hybrid layout combines a dynamic woofer, six balanced armatures and two electrostatic tweeters.
Cons: Those measurements show a 5.6 dB dip near 6.5 kHz and treble about 2.6 dB below target, which softens cymbal attack slightly. Air above 10 kHz rises about 3.4 dB over target, peaking near 11.8 kHz, which listeners sensitive to treble may hear as a touch of glare.
Full ThieAudio Monarch MKII review and specifications →
| Released | Oct 2021 (5 years ago) |
|---|---|
| Back | Closed |
| Connection | Wired |
| Deviation From Target | 1.45 dB standard deviation |
| Driver Type | Hybrid (1 dynamic + 6 balanced armature + 2 electrostatic) |
| Drivers | 1 x 10mm dynamic + 6 x balanced armature + 2 x electrostatic |
| Form Factor | In-ear |
| Frequency Response | 20Hz - 20kHz (Manufacturer specified) |
| Harman Preference Score | 81 (measured by crinacle, via AutoEQ) |
| Impedance | 36 ohms |
| Sensitivity | 108 dB/mW |
| Sub-bass Extension | Within 6 dB of target down to 20 Hz (-0.3 dB at 30 Hz) |
| Tonal Tilt | -0.22 (negative is warmer, positive brighter) |
EQ preset to match the Harman target
Set a preamp of -3.6 dB, then add these filters in any parametric equalizer (Wavelet, Equalizer APO, Peace, or a player with parametric EQ). Calculated by AutoEQ from its measured frequency response.
| Filter | Frequency | Gain | Q |
|---|---|---|---|
| Low shelf | 105 Hz | +0.1 dB | 0.70 |
| Peak | 6,833 Hz | +3.8 dB | 2.05 |
| Peak | 2,005 Hz | -1.3 dB | 1.08 |
| Peak | 319 Hz | -0.9 dB | 1.20 |
| Peak | 9,387 Hz | +2.0 dB | 3.00 |
| High shelf | 10,000 Hz | -2.6 dB | 0.70 |
| Peak | 4,445 Hz | +2.7 dB | 6.00 |
| Peak | 5,134 Hz | -2.0 dB | 6.00 |
| Peak | 811 Hz | +0.4 dB | 2.29 |
| Peak | 81 Hz | +0.3 dB | 1.93 |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
ThieAudio Monarch MKIV: $1,149.00 Linsoul eBay
Pros: Across 14 squig.link measurements it posts a preference score of 79.0 with a very smooth 1.31 dB spread. Sub-bass and bass sit within half a dB of target, so the dual 8 mm dynamic drivers give clean, accurate low end, and a 5 dB air lift near 12 kHz from the electrostatic tweeters adds shimmer and space. It rates above the SoftEars RSV.
Cons: Presence sits 2.7 dB below target with a 3.7 dB dip near 6.4 kHz, so vocals and strings lose some immediacy. The Moondrop Dark Saber rates well above it for less money, and the Symphonium Audio Helios rates higher at a similar price.
Full ThieAudio Monarch MKIV review and specifications →
| Released | Jul 2025 (1 year ago) |
|---|---|
| Back | Closed |
| Built-in Microphone | No |
| Connection | Wired |
| Deviation From Target | 1.31 dB standard deviation |
| Driver Type | Hybrid (2 dynamic + 6 balanced armature + 2 electrostatic) |
| Drivers | 2 x 8mm dynamic + 6 x balanced armature + 2 x electrostatic |
| Form Factor | In-ear |
| Frequency Response | 10Hz - 44kHz (Manufacturer specified) |
| Harman Preference Score | 79 (median of 14 squig.link measurements, calibrated to AutoEQ) |
| Sensitivity | 100 dB |
| Sub-bass Extension | Within 6 dB of target down to 20 Hz (-0.2 dB at 30 Hz) |
| Tonal Tilt | -0.43 (negative is warmer, positive brighter) |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons