Short answer: a tie on sound quality. Both are rated 3.3/5 (#957 and #917 of 1369 in-ear headphones) at nearly the same price ($49 vs $49.99), so choose on features and fit.
Why pick the HeartField Blanc: A published AutoEQ preset corrects its response toward the Harman target, so a few minutes of EQ setup closes most of the gap. The catch: An uneven response, 2.8 dB standard deviation from target.
What the KZ ZSX does well: 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. The catch: 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 HeartField Blanc or the KZ ZSX on features: they are rated the same for sound quality at close to the same price.
Looking for alternatives? See the complete Headphones rankings.
A published AutoEQ preset corrects its response toward the Harman target, so a few minutes of EQ setup closes most of the gap.
Linsoul 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 17, 2026 at 6:04 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
| HeartField Blanc | KZ ZSX | |
|---|---|---|
| Price | 49.00 | $49.99 |
| Ranked | #957 of 1369 in In-Ear Headphones | #917 of 1369 in In-Ear Headphones |
| Form Factor | In-ear | In-ear |
| Back | Closed | Closed |
| Harman Preference Score | 65 (median of 3 squig.link measurements, calibrated to AutoEQ) | 65 (measured by crinacle, via AutoEQ) |
| Deviation From Target | 2.83 dB standard deviation | 2.73 dB standard deviation |
| Tonal Tilt | +0.22 (negative is warmer, positive brighter) | -0.63 (negative is warmer, positive brighter) |
| Sub-bass Extension | Within 6 dB of target down to 20 Hz (-3.5 dB at 30 Hz) | Within 6 dB of target down to 20 Hz (-0.9 dB at 30 Hz) |
| Driver Type | Balanced Armature | Hybrid (1 dynamic + 5 balanced armature) |
| Drivers | 5 balanced armature drivers per side | 1 x dynamic + 5 x balanced armature |
| Impedance | 15 ohms | 24 ohms |
| Connection | Wired | Wired |
| Sensitivity | - | 111 dB |
| Frequency Response | - | 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 HeartField Blanc from dl, gadgetrytech, jaytiss and silicagel; the KZ ZSX from aden, bassyalexander, eplv, harutohiroki, lown-fi, melatonin, pw and vortexreviews, all via squig.link.
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