Short answer: the KZ Castor. It ranks #297 of 450 in-ear headphones by sound quality, rated 3.9/5, at $20.89; the KZ ZST ranks #336, rated 3.7/5, and costs $21.99, so there is little reason to consider the other one.
The case for the KZ ZST: In oratory1990’s measurement the preference score is 70, with bass about 2.3 dB above target from 60 to 200 Hz for extra warmth and punch, and sub-bass tracking the target within 0.1 dB. The catch: A 9.4 dB dip near 4.4 kHz and 3.7 dB lower presence from 3 to 6 kHz pull back vocal clarity and the attack of snares and guitars.
Buy the KZ Castor. It is rated higher for sound quality than the KZ ZST and costs less, so only choose the other one for a particular feature it does better.
Looking for alternatives? See the complete Headphones rankings.
Specifications Side By Side
| KZ Castor | KZ ZST | |
|---|---|---|
| Price | $20.89 | $21.99 |
| Ranked | #297 of 450 in In-Ear Headphones | #336 of 450 in In-Ear Headphones |
| Form Factor | In-ear | In-ear |
| Back | Closed | Closed |
| Harman Preference Score | 73 (median of 11 squig.link measurements, calibrated to AutoEQ) | 70 (measured by oratory1990, via AutoEQ) |
| Deviation From Target | 2.01 dB standard deviation | 2.31 dB standard deviation |
| Tonal Tilt | -0.29 (negative is warmer, positive brighter) | -0.47 (negative is warmer, positive brighter) |
| Sub-bass Extension | Within 6 dB of target down to 20 Hz (-0.0 dB at 30 Hz) | Within 6 dB of target down to 20 Hz (+0.1 dB at 30 Hz) |
| Connection | Wired | Wired |
| Driver Type | Dynamic | Hybrid (1 dynamic + 1 balanced armature) |
| Drivers | 2 x dynamic | 1 x 10mm dynamic + 1 x balanced armature |
| Sensitivity | 105 dB | - |
| Frequency Response | 20Hz - 40kHz (Manufacturer specified) | 20Hz - 20kHz (Manufacturer specified) |
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- KZ Castor vs TANGZU Wan’er S.G
Prices on this page were last checked October 11, 2026 at 4:59 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
KZ Castor: $20.89 Amazon eBay
Full KZ Castor review and specifications →
| Back | Closed |
|---|---|
| Connection | Wired |
| Deviation From Target | 2.01 dB standard deviation |
| Driver Type | Dynamic |
| Drivers | 2 x dynamic |
| Form Factor | In-ear |
| Frequency Response | 20Hz - 40kHz (Manufacturer specified) |
| Harman Preference Score | 73 (median of 11 squig.link measurements, calibrated to AutoEQ) |
| Sensitivity | 105 dB |
| Sub-bass Extension | Within 6 dB of target down to 20 Hz (-0.0 dB at 30 Hz) |
| Tonal Tilt | -0.29 (negative is warmer, positive brighter) |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
KZ ZST: $21.99 Amazon eBay
Pros: In oratory1990’s measurement the preference score is 70, with bass about 2.3 dB above target from 60 to 200 Hz for extra warmth and punch, and sub-bass tracking the target within 0.1 dB. The low mids and upper mids stay within about 1 dB, so vocals and instruments sit naturally. The warm and bassy profiles fit it best, and the hybrid pairing of one dynamic and one balanced armature driver costs very little.
Cons: A 9.4 dB dip near 4.4 kHz and 3.7 dB lower presence from 3 to 6 kHz pull back vocal clarity and the attack of snares and guitars. Above 10 kHz the response runs about 6.5 dB hot, with a 10 dB peak near 11 kHz that adds sharpness to cymbals. The TANGZU Wan’er S.G rates higher.
Full KZ ZST review and specifications →
| Released | 2016 (10 years ago) |
|---|---|
| Back | Closed |
| Connection | Wired |
| Deviation From Target | 2.31 dB standard deviation |
| Driver Type | Hybrid (1 dynamic + 1 balanced armature) |
| Drivers | 1 x 10mm dynamic + 1 x balanced armature |
| Form Factor | In-ear |
| Frequency Response | 20Hz - 20kHz (Manufacturer specified) |
| Harman Preference Score | 70 (measured by oratory1990, via AutoEQ) |
| Sub-bass Extension | Within 6 dB of target down to 20 Hz (+0.1 dB at 30 Hz) |
| Tonal Tilt | -0.47 (negative is warmer, positive brighter) |
EQ preset to match the Harman target
Set a preamp of -4.5 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 | -0.2 dB | 0.70 |
| Peak | 182 Hz | -3.0 dB | 0.62 |
| Peak | 620 Hz | +2.4 dB | 0.63 |
| Peak | 9,298 Hz | -3.1 dB | 3.37 |
| Peak | 1,878 Hz | -4.1 dB | 3.05 |
| High shelf | 10,000 Hz | -0.3 dB | 0.70 |
| Peak | 4,253 Hz | +4.7 dB | 4.05 |
| Peak | 1,321 Hz | -0.6 dB | 2.60 |
| Peak | 3,462 Hz | -1.0 dB | 6.00 |
| Peak | 358 Hz | -0.0 dB | 5.65 |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons