Short answer: the KZ Linlong. It ranks #625 of 1291 in-ear headphones by sound quality, rated 3.8/5, at $15; the 7Hz Aero ranks #627, rated 3.7/5, at $14.99. The price gap is small enough that the sound-quality ranking should decide it.
Why pick the KZ Linlong: A broadly balanced tuning with a preference score of 71 against the Harman target. The catch: Treble about 2 dB below target from 3 to 10 kHz, which can sound dull or veiled next to brighter headphones.
The case for the 7Hz Aero: Across eight hobbyist measurements on squig.link it earns a Harman preference score of 70.6 with a smooth 1.97 dB deviation, an unusually even response for such an inexpensive single 9.2mm dynamic earphone. The tradeoff: The 10 to 16 kHz air region runs about 5.3 dB above target, and a 5.3 dB peak near 8.4 kHz can make cymbals and sibilance a little splashy on bright recordings.
Buy the KZ Linlong. It is rated higher for sound quality, and the $0.01 you would save on the 7Hz Aero does not close the gap.
Still deciding? The full Headphones rankings cover every ranked option.
A broadly balanced tuning with a preference score of 71 against the Harman target.
KZ Audio $15.00 eBay
Across eight hobbyist measurements on squig.link it earns a Harman preference score of 70.6 with a smooth 1.97 dB deviation, an unusually even response for such an inexpensive single 9.2mm dynamic earphone.
Amazon $14.99 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.
As an eBay Partner, we may be compensated if you make a purchase.
Specifications Side By Side
| KZ Linlong | 7Hz Aero | |
|---|---|---|
| Price | $15.00 | $14.99 |
| Ranked | #625 of 1291 in In-Ear Headphones | #627 of 1291 in In-Ear Headphones |
| Form Factor | In-ear | In-ear |
| Back | Closed | Closed |
| Harman Preference Score | 71 (median of 3 squig.link measurements, calibrated to AutoEQ) | 71 (median of 8 squig.link measurements, calibrated to AutoEQ) |
| Deviation From Target | 1.96 dB standard deviation | 1.97 dB standard deviation |
| Tonal Tilt | -0.87 (negative is warmer, positive brighter) | -0.81 (negative is warmer, positive brighter) |
| Sub-bass Extension | Within 6 dB of target down to 20 Hz (+3.2 dB at 30 Hz) | Within 6 dB of target down to 20 Hz (+2.8 dB at 30 Hz) |
| Connection | Wired | Wired |
| Driver Type | Dynamic | Dynamic |
| Drivers | 1 x 6mm micro dynamic driver (XUN-6) | 1 x 9.2mm dynamic |
| Impedance | 25 ohms | - |
| Sensitivity | 103 dB | - |
| Frequency Response | 20Hz - 40kHz | - |
| Weight | 0 lbs (18 g) | - |
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 KZ Linlong from aftersound, ianfann and tonedeafmonk; the 7Hz Aero from achoreviews, aftersound, bassyalexander, musicafe, pw, silicagel, soundcheck39 and vortexreviews, all via squig.link.
Related Headphone Comparisons
More top alternatives to KZ Linlong: