Short answer: the QoA x Eir Aoi Misty Blue. It ranks #670 of 1291 in-ear headphones by sound quality, rated 3.7/5, at $249; the 7Hz Eternal ranks #691, rated 3.6/5, at $249. The price gap is small enough that the sound-quality ranking should decide it.
Why pick the QoA x Eir Aoi Misty Blue: A collaboration with singer Eir Aoi, with two dynamic drivers and two balanced armatures. The catch: Treble sits about 4.4 dB below target, a dark, relaxed balance.
Why pick the 7Hz Eternal: Crinacle’s measurement gives it a preference score of 69, and squig.link measurements show bass, mids and upper mids all within about 1 dB of target, so voices and instruments sound natural. The catch: Treble above 6 kHz drops 3 to 4 dB below target with an 8.7 dB dip near 10.6 kHz, so cymbals lack sparkle and detail sounds dim.
Buy the QoA x Eir Aoi Misty Blue. It is rated higher for sound quality than the 7Hz Eternal at the same price, which makes it the one to get unless you need something the other one does better.
Want more options? Browse the full Headphones rankings.
A collaboration with singer Eir Aoi, with two dynamic drivers and two balanced armatures.
e-earphone (JP) eBay
Crinacle’s measurement gives it a preference score of 69, and squig.link measurements show bass, mids and upper mids all within about 1 dB of target, so voices and instruments sound natural.
Linsoul $249.00 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
| QoA x Eir Aoi Misty Blue | 7Hz Eternal | |
|---|---|---|
| Price | $249 | $249.00 |
| Ranked | #670 of 1291 in In-Ear Headphones | #691 of 1291 in In-Ear Headphones |
| Form Factor | In-ear | In-ear |
| Back | Closed | Closed |
| Connection | Wired | Wired |
| Driver Type | Hybrid | Dynamic |
| Drivers | 2 x dynamic + 2 x balanced armature | 1 x 14.5mm dynamic |
| Impedance | 30 ohms | 30 ohms |
| Sensitivity | 105 dB +/-2 dB | 109 dB/1kHz |
| Harman Preference Score | 70 (median of 6 squig.link measurements, calibrated to AutoEQ) | 69 (measured by crinacle, via AutoEQ) |
| Deviation From Target | 2.11 dB standard deviation | 2.63 dB standard deviation |
| Tonal Tilt | -0.65 (negative is warmer, positive brighter) | -0.36 (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 (-2.0 dB at 30 Hz) |
| Weight | - | 0 lbs (6 g) per earbud |
| Frequency Response | - | 10Hz - 20kHz (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 QoA x Eir Aoi Misty Blue from aftersound, audioamigo, bassaudio, hu-fi, jaytiss, practiphile, pw and soundcheck39; the 7Hz Eternal from audioamigo, bedrock, dchpgall, dl, harpo, hbb, iemworld, musicafe, precog, vortexreviews and vsg, all via squig.link.
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