Short answer: the Tanchjim Oxygen. It ranks #210 of 1291 in-ear headphones by sound quality, rated 4.3/5, at $279.99. The Kiwi Ears Septet ranks #278, rated 4.2/5, at $269, $10.99 cheaper, not enough of a saving to outweigh the sound-quality gap.
The case for the Tanchjim Oxygen: Crinacle’s measurement gives it a preference score of 77, and across 22 hobbyist measurements its sub-bass lands right on target at 30 Hz, giving full, extended low end from a single 9.2 mm dynamic driver. The tradeoff: The presence band from 3 to 6 kHz falls about 2.2 dB short and a 4.7 dB dip near 10 kHz dulls cymbal edges and sibilants, in squig.link measurements.
Why pick the Kiwi Ears Septet: The median of 29 hobbyist measurements gives it a very good Harman preference score of 76 with a 1.77 dB spread. The tradeoff: Presence sits about 3 dB low with a 5.5 dB dip near 3.4 kHz, so vocals and instruments lose some bite.
Buy the Tanchjim Oxygen. It is rated higher for sound quality, and the $10.99 saving on the Kiwi Ears Septet is not enough to make up the difference.
Looking for alternatives? See the complete Headphones rankings.
Crinacle’s measurement gives it a preference score of 77, and across 22 hobbyist measurements its sub-bass lands right on target at 30 Hz, giving full, extended low end from a single 9.2 mm dynamic driver.
Apos Audio $279.99 eBay
The median of 29 hobbyist measurements gives it a very good Harman preference score of 76 with a 1.77 dB spread.
Amazon $269.00 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
| Tanchjim Oxygen | Kiwi Ears Septet | |
|---|---|---|
| Price | $279.99 | $269.00 |
| Ranked | #210 of 1291 in In-Ear Headphones | #278 of 1291 in In-Ear Headphones |
| Form Factor | In-ear | In-ear |
| Back | Closed | Closed |
| Harman Preference Score | 77 (measured by crinacle, via AutoEQ) | 76 (median of 29 squig.link measurements, calibrated to AutoEQ) |
| Deviation From Target | 2.08 dB standard deviation | 1.77 dB standard deviation |
| Tonal Tilt | -0.01 (negative is warmer, positive brighter) | -0.38 (negative is warmer, positive brighter) |
| Sub-bass Extension | Within 6 dB of target down to 20 Hz (+0.1 dB at 30 Hz) | Within 6 dB of target down to 20 Hz (+0.3 dB at 30 Hz) |
| Connection | Wired | Wired |
| Driver Type | Dynamic | Hybrid (1 dynamic + 4 balanced armature + 1 planar + 1 piezoelectric) |
| Drivers | 1 x 9.2mm dynamic | 1 x 10mm dynamic + 4 x balanced armature + 1 x micro planar + 1 x piezoelectric |
| Impedance | 32 ohms | 15 ohms |
| Sensitivity | 110 dB | 95 dB/mW |
| Frequency Response | 10Hz - 40kHz (Manufacturer specified) | 8Hz - 30kHz (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 Tanchjim Oxygen from aftersound, ankramutt, atechreviews, boizoff, bryaudioreviews, bukanaudiophile, csi-zone, dchpgall, dentreviews, harutohiroki, hu-fi, iemworld, kuping-sensi, musicafe, precog, recode, rg, soundignity, superreview, tanchjim, therollo9, timmyv and zerostresslevel; the Kiwi Ears Septet from aden, aftersound, arn, atechreviews, audioamigo, avishai, bassaudio, boizoff, cqtek, dl, ducbloke, flare, hobbytalk, hu-fi, iemocean, jaytiss, joycesreview, kazi, kuping-sensi, lumerion, obodio, practiphile, pw, silicagel, soundcheck39, soundignity, timmyv, tonedeafmonk and vortexreviews, all via squig.link.
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