Short answer: the ThieAudio Legacy 4. It ranks #28 of 865 in-ear headphones by sound quality (rated 4.8/5) at $50.99 and is still sold new; the ThieAudio Legacy 9 ranks #720 (rated 2.6/5) and is discontinued, so it is only an option used.
The ThieAudio Legacy 4 is the better-sounding pick. The Legacy 4 pairs one dynamic driver with three balanced armatures, and the median of twelve hobbyist measurements on squig.link shows bass essentially on target, slightly above it at 30 Hz. The catch: A 4.3 dB dip near 3.75 kHz and a presence band about 2.3 dB low can push vocals back and soften the attack of guitars and snares.
Why pick the ThieAudio Legacy 9: Bass is lifted about 3.7 dB with extension to 20 Hz, giving kick drums and bass lines extra weight. Watch for: Discontinued, so it is mainly found used.
Buy the ThieAudio Legacy 4. It is rated higher for sound quality; the ThieAudio Legacy 9 is no longer sold new.
Still deciding? The full Headphones rankings cover every ranked option.
Specifications Side By Side
| ThieAudio Legacy 4 | ThieAudio Legacy 9 | |
|---|---|---|
| Price | $50.99 | Discontinued |
| Ranked | #28 of 865 in In-Ear Headphones | #720 of 865 in In-Ear Headphones |
| Form Factor | In-ear | In-ear |
| Back | Closed | - |
| Harman Preference Score | 84 (median of 12 squig.link measurements, calibrated to AutoEQ) | 56 (measured by crinacle, via AutoEQ) |
| Deviation From Target | 1.19 dB standard deviation | 3.11 dB standard deviation |
| Tonal Tilt | -0.10 (negative is warmer, positive brighter) | -1.33 (negative is warmer, positive brighter) |
| Sub-bass Extension | Within 6 dB of target down to 20 Hz (+0.4 dB at 30 Hz) | Within 6 dB of target down to 20 Hz (+2.1 dB at 30 Hz) |
| Connection | Wired | Wired |
| Driver Type | Hybrid (1 dynamic + 3 balanced armature) | Hybrid |
| Drivers | 1 x 8mm dynamic + 3 x balanced armature | 1 x 10mm dynamic + 8 x balanced armature |
| Impedance | 9.4 ohms | 18 ohms |
| Sensitivity | 108 dB | - |
| Frequency Response | 20Hz - 20kHz (Manufacturer specified) | 20Hz - 28kHz |
| Built-in Microphone | No | - |
Related Headphone Comparisons
More worthwhile head-to-heads for ThieAudio Legacy 4:
- EPZ G20 vs ThieAudio Legacy 4
- ThieAudio Legacy 4 vs Ooopusx OP24
- ThieAudio Legacy 4 vs CCA Rhapsody
- ThieAudio Legacy 2 vs ThieAudio Legacy 4
- ThieAudio Legacy 4 vs ThieAudio Legacy 5
Prices on this page were last checked October 13, 2026 at 3:17 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 Legacy 4: $50.99 Amazon $50.99 eBay
Same family: the ThieAudio Legacy 2 (lower-end model, ranked lower, rated 4.1/5).
Pros: The Legacy 4 pairs one dynamic driver with three balanced armatures, and the median of twelve hobbyist measurements on squig.link shows bass essentially on target, slightly above it at 30 Hz. With about 1.2 dB of unevenness and a preference score of 84, its bass, mids and treble sit within half a dB of target on average. It rates higher than the less expensive CCA Phoenix, and 108 dB sensitivity makes it easy to drive.
Cons: A 4.3 dB dip near 3.75 kHz and a presence band about 2.3 dB low can push vocals back and soften the attack of guitars and snares. There is no microphone, and the EPZ G20 and EPZ Q1 Pro both rate higher while costing a little less.
Full ThieAudio Legacy 4 review and specifications →
| Back | Closed |
|---|---|
| Built-in Microphone | No |
| Connection | Wired |
| Deviation From Target | 1.19 dB standard deviation |
| Driver Type | Hybrid (1 dynamic + 3 balanced armature) |
| Drivers | 1 x 8mm dynamic + 3 x balanced armature |
| Form Factor | In-ear |
| Frequency Response | 20Hz - 20kHz (Manufacturer specified) |
| Harman Preference Score | 84 (median of 12 squig.link measurements, calibrated to AutoEQ) |
| Impedance | 9.4 ohms |
| Sensitivity | 108 dB |
| Sub-bass Extension | Within 6 dB of target down to 20 Hz (+0.4 dB at 30 Hz) |
| Tonal Tilt | -0.10 (negative is warmer, positive brighter) |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
ThieAudio Legacy 9 Discontinued eBay
Pros: Bass is lifted about 3.7 dB with extension to 20 Hz, giving kick drums and bass lines extra weight. Upper treble lifts about 4.7 dB for extra air and sparkle. Lower mids sit within about 0.5 dB of target, keeping voices and guitars natural. It uses 1 x 10mm dynamic + 8 x balanced armature with an easy 18 ohm load.
Cons: Discontinued, so it is mainly found used. Presence sits about 6 dB low with a 9.2 dB dip near 5.4 kHz, so vocals and instruments lose some bite. A 4.4 dB peak near 11.9 kHz can make cymbals and sibilance sound sharp. A Harman score of 56 places it in the lower part of the in-ear rankings.
Full ThieAudio Legacy 9 review and specifications →
| Connection | Wired |
|---|---|
| Deviation From Target | 3.11 dB standard deviation |
| Driver Type | Hybrid |
| Drivers | 1 x 10mm dynamic + 8 x balanced armature |
| Form Factor | In-ear |
| Frequency Response | 20Hz - 28kHz |
| Harman Preference Score | 56 (measured by crinacle, via AutoEQ) |
| Impedance | 18 ohms |
| Sub-bass Extension | Within 6 dB of target down to 20 Hz (+2.1 dB at 30 Hz) |
| Tonal Tilt | -1.33 (negative is warmer, positive brighter) |
EQ preset to match the Harman target
Set a preamp of -6.4 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 | -3.4 dB | 0.70 |
| Peak | 180 Hz | -3.5 dB | 0.96 |
| Peak | 4,893 Hz | +4.6 dB | 0.69 |
| Peak | 833 Hz | +2.4 dB | 1.48 |
| Peak | 1,834 Hz | -3.9 dB | 1.35 |
| High shelf | 10,000 Hz | -4.9 dB | 0.70 |
| Peak | 65 Hz | +0.6 dB | 2.16 |
| Peak | 5,028 Hz | +2.6 dB | 5.44 |
| Peak | 4,005 Hz | -1.3 dB | 5.78 |
| Peak | 6,081 Hz | -1.5 dB | 6.00 |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons