Short answer: the Astrotec GX100. It ranks #859 of 1291 in-ear headphones by sound quality, rated 3.4/5, at $49.90; the KZ ZSX ranks #901, rated 3.3/5, and costs $49.99, so there is not much of a tradeoff to weigh.
The case for the Astrotec GX100: A broadly balanced tuning with a preference score of 67 against the Harman target. The catch: Treble about 2 dB above target from 3 to 10 kHz, which can sound sharp or tiring at higher volume.
The case for the KZ ZSX: A one dynamic plus five balanced armature hybrid at a budget price, with sub-bass within 1 dB of target and midbass about 2.4 dB above it, so electronic and hip hop tracks get punchy, full lows. Watch for: Across eight hobbyist measurements on squig.link a 10 dB peak near 11.9 kHz stands out, which can make cymbals and hi hats sound splashy and tizzy, while a 6.8 dB dip near 6.5 kHz leaves the treble uneven.
Buy the Astrotec GX100. It is rated higher for sound quality than the KZ ZSX and costs less, so only choose the other one for a particular feature it does better.
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A broadly balanced tuning with a preference score of 67 against the Harman target.
Astrotec $49.90 eBay
A one dynamic plus five balanced armature hybrid at a budget price, with sub-bass within 1 dB of target and midbass about 2.4 dB above it, so electronic and hip hop tracks get punchy, full lows.
Linsoul $49.99 eBayPrices on this page were last checked October 16, 2026 at 5:46 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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Specifications Side By Side
| Astrotec GX100 | KZ ZSX | |
|---|---|---|
| Price | $49.90 | $49.99 |
| Ranked | #859 of 1291 in In-Ear Headphones | #901 of 1291 in In-Ear Headphones |
| Form Factor | In-ear | In-ear |
| Back | Closed | Closed |
| Harman Preference Score | 67 (median of 4 squig.link measurements, calibrated to AutoEQ) | 65 (measured by crinacle, via AutoEQ) |
| Deviation From Target | 2.39 dB standard deviation | 2.73 dB standard deviation |
| Tonal Tilt | +0.98 (negative is warmer, positive brighter) | -0.63 (negative is warmer, positive brighter) |
| Sub-bass Extension | Within 6 dB of target down to 20 Hz (-4.3 dB at 30 Hz) | Within 6 dB of target down to 20 Hz (-0.9 dB at 30 Hz) |
| Connection | Wired | Wired |
| Driver Type | Hybrid | Hybrid (1 dynamic + 5 balanced armature) |
| Drivers | 1 DD + 1 PZT (1 x 10mm LCP dynamic driver + 1 x 10.6mm piezoelectric ceramic driver) | 1 x dynamic + 5 x balanced armature |
| Impedance | 32 ohms | 24 ohms |
| Sensitivity | 108 dB | 111 dB |
| Frequency Response | 5Hz - 40kHz | 7Hz - 40kHz (Manufacturer specified) |
Frequency Response Compared
Both headphones’ measurements overlaid on the Harman target. Above the target sounds louder in that range, below it quieter. Each curve is the median of several independent measurements, shifted so its 500 Hz to 2 kHz average sits at 0 dB, so only the tuning is compared.
Measurement data: the Astrotec GX100 from audioamigo, pw, soundcheck39 and tonedeafmonk; the KZ ZSX from aden, bassyalexander, eplv, harutohiroki, lown-fi, melatonin, pw and vortexreviews, all via squig.link.
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