Short answer: the 7Hz Sonus II. It ranks #258 of 1291 in-ear headphones by sound quality, rated 4.2/5, at $75.99; the KZ Zenith ranks #328, rated 4.1/5, at $75.99. With prices this close, go by the sound-quality ranking rather than the cost.
Why pick the 7Hz Sonus II: A hybrid dynamic and planar in-ear with a 76.5 preference score, a smooth 1.7 dB deviation and slightly warm, natural bass. Watch for: The 3 to 6 kHz presence range sits nearly 4 dB under target with a 5.2 dB dip near 6 kHz, so vocals and guitars can sound a little distant and less crisp.
What the KZ Zenith does well: The median of 10 hobbyist measurements gives it a very good Harman preference score of 75 with a 1.89 dB spread, and its mids sit within about 0.5 dB of target, so vocals and instruments sound natural. Watch for: Presence sits about 3.6 dB low with a 5 dB dip near 5.8 kHz, so vocals and instruments lose some bite.
Buy the 7Hz Sonus II. It is rated higher for sound quality than the KZ Zenith at the same price, so it is the default pick unless a specific strength of the other one matters more to you.
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A hybrid dynamic and planar in-ear with a 76.5 preference score, a smooth 1.7 dB deviation and slightly warm, natural bass.
Amazon $75.99 eBay
The median of 10 hobbyist measurements gives it a very good Harman preference score of 75 with a 1.89 dB spread, and its mids sit within about 0.5 dB of target, so vocals and instruments sound natural.
Amazon $75.99 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
| 7Hz Sonus II | KZ Zenith | |
|---|---|---|
| Price | $75.99 | $75.99 |
| Ranked | #258 of 1291 in In-Ear Headphones | #328 of 1291 in In-Ear Headphones |
| Form Factor | In-ear | In-ear |
| Back | Closed | Closed |
| Harman Preference Score | 77 (median of 2 squig.link measurements, calibrated to AutoEQ) | 75 (median of 10 squig.link measurements, calibrated to AutoEQ) |
| Deviation From Target | 1.66 dB standard deviation | 1.89 dB standard deviation |
| Tonal Tilt | -0.45 (negative is warmer, positive brighter) | -0.28 (negative is warmer, positive brighter) |
| 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 (-1.7 dB at 30 Hz) |
| Connection | Wired | Wired |
| Driver Type | Hybrid (1 dynamic + 1 planar magnetic) | Dynamic |
| Drivers | 1 x dynamic + 1 x planar magnetic | 1 x dynamic (Driver X) |
| Impedance | 29 ohms | 41 ohms |
| Sensitivity | 108 dB/V | 128 dB |
| Frequency Response | 10Hz - 20kHz (Manufacturer specified) | 20Hz - 40kHz (Manufacturer specified) |
| Built-in Microphone | - | No |
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 7Hz Sonus II from aftersound, bassaudio and jaytiss; the KZ Zenith from audioamigo, doltonius, eplv, koi, lown-fi, obodio, practiphile, pw, regancipher and soundignity, all via squig.link.
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