Short answer: a tie on sound quality. Both are rated 4.3/5 (#189 and #203 of 1291 in-ear headphones) at nearly the same price ($20.99 vs $20), so choose on features and fit.
Why pick the CCA Duo: The median of 12 hobbyist measurements gives it a very good Harman preference score of 78 with a 1.61 dB spread, and its mids sit within about 0.5 dB of target, so vocals and instruments sound natural. The catch: Sub-bass is 3.6 dB short at 30 Hz, so deep bass lacks rumble.
The case for the TANCHJIM ZERO DSP: A broadly balanced tuning with a preference score of 78 against the Harman target. Watch for: Treble about 2 dB above target from 3 to 10 kHz, which can sound sharp or tiring at higher volume.
Buy the CCA Duo or the TANCHJIM ZERO DSP on features: they are rated the same for sound quality at close to the same price.
Looking for alternatives? See the complete Headphones rankings.
The median of 12 hobbyist measurements gives it a very good Harman preference score of 78 with a 1.61 dB spread, and its mids sit within about 0.5 dB of target, so vocals and instruments sound natural.
Amazon $20.99 eBay
A broadly balanced tuning with a preference score of 78 against the Harman target.
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Specifications Side By Side
| CCA Duo | TANCHJIM ZERO DSP | |
|---|---|---|
| Price | $20.99 | $20 |
| Ranked | #189 of 1291 in In-Ear Headphones | #203 of 1291 in In-Ear Headphones |
| Form Factor | In-ear | In-ear |
| Back | Closed | Closed |
| Harman Preference Score | 78 (median of 12 squig.link measurements, calibrated to AutoEQ) | 78 (median of 3 squig.link measurements, calibrated to AutoEQ) |
| Deviation From Target | 1.61 dB standard deviation | 1.49 dB standard deviation |
| Tonal Tilt | +0.49 (negative is warmer, positive brighter) | +0.09 (negative is warmer, positive brighter) |
| Sub-bass Extension | Within 6 dB of target down to 20 Hz (-3.6 dB at 30 Hz) | Within 6 dB of target down to 20 Hz (+0.6 dB at 30 Hz) |
| Connection | Wired | USB-C |
| Driver Type | Dynamic | Dynamic |
| Drivers | 2 x 7mm dynamic | 1 x 10mm dynamic |
| Impedance | 18 ohms | 32 ohms |
| Sensitivity | 106 dB/mW | 118 dB/Vrms |
| Frequency Response | 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 CCA Duo from ankramutt, arn, enemyspider, harpo, ianfann, isaiahse, obodio, practiphile, pw, soundcheck39, therollo9 and tonedeafmonk; the TANCHJIM ZERO DSP from hobbytalk, tanchjim and therollo9, all via squig.link.
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