Short answer: the DUNU SA6 EST. It ranks #810 of 1291 in-ear headphones by sound quality, rated 3.5/5, at $619. The OpenAudio Mercury ranks #900, rated 3.3/5, at $599.99, $19.01 cheaper, not enough of a saving to outweigh the sound-quality gap.
What the DUNU SA6 EST does well: A broadly balanced tuning with a preference score of 68 against the Harman target. Watch for: Treble about 6 dB below target from 3 to 10 kHz, which can sound dull or veiled next to brighter headphones.
Why pick the OpenAudio Mercury: A bass-forward tuning with about 4.7 dB of extra sub-bass below 60 Hz and a 5.8 dB lift at 30 Hz, so kick drums and synth bass carry deep rumble. Watch for: A 6.6 dB dip near 5.9 kHz in squig.link measurements softens vocal consonants and the leading edge of guitars and snares.
Buy the DUNU SA6 EST. It is rated higher for sound quality, and saving $19.01 with the OpenAudio Mercury does not make up for the sound-quality gap.
Want more options? Browse the full Headphones rankings.
A broadly balanced tuning with a preference score of 68 against the Harman target.
Amazon $619 eBay
A bass-forward tuning with about 4.7 dB of extra sub-bass below 60 Hz and a 5.8 dB lift at 30 Hz, so kick drums and synth bass carry deep rumble.
Shenzhenaudio $599.99 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
| DUNU SA6 EST | OpenAudio Mercury | |
|---|---|---|
| Price | $619 | $599.99 |
| Ranked | #810 of 1291 in In-Ear Headphones | #900 of 1291 in In-Ear Headphones |
| Form Factor | In-ear | In-ear |
| Back | Closed | Closed |
| Harman Preference Score | 68 (median of 7 squig.link measurements, calibrated to AutoEQ) | 65 (measured by crinacle, via AutoEQ) |
| Deviation From Target | 2.55 dB standard deviation | 2.46 dB standard deviation |
| Tonal Tilt | -0.41 (negative is warmer, positive brighter) | -1.07 (negative is warmer, positive brighter) |
| Sub-bass Extension | Within 6 dB of target down to 20 Hz (-2.5 dB at 30 Hz) | Within 6 dB of target down to 20 Hz (+5.8 dB at 30 Hz) |
| Connection | Wired (3.5mm / 4.4mm modular) | Wired |
| Driver Type | Tribrid | Hybrid (1 dynamic + 4 balanced armature) |
| Drivers | 6 Balanced Armature, 2 Electrostatic | 1 x 9.2mm dynamic + 4 x balanced armature |
| Impedance | - | 8 ohms |
| Sensitivity | - | 110 dB/mW |
| Frequency Response | - | 5Hz - 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 DUNU SA6 EST from atechreviews, ducbloke, eliseaudio, kazi, precog, soundignity and superreview; the OpenAudio Mercury from atechreviews, bukanaudiophile, hbb, precog and superreview, all via squig.link.
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