Short answer: the Fearless Audio S6Rui. It ranks #372 of 450 in-ear headphones by sound quality, rated 3.3/5, at $389; the Cayin Fantasy ranks #395, rated 3.0/5, and costs $399, so there is little reason to consider the other one.
The case for the Fearless Audio S6Rui: Six balanced armature drivers per side earn a preference score of 65 in crinacle’s measurement, a serviceable match to the Harman target. Watch for: A 2.7 dB standard deviation from target points to an uneven response that benefits from some EQ.
What the Cayin Fantasy does well: Its single 10.3mm dynamic driver at 37 ohms and 108 dB runs from a phone without strain. The catch: Crinacle’s measurement gives it a preference score of only 61.0, and squig.link hobbyist measurements show treble about 5.5 dB hot with a 12.4 dB peak near 11.2 kHz, so cymbals and sibilance can turn harsh.
Buy the Fearless Audio S6Rui. It is rated higher for sound quality than the Cayin Fantasy and costs less, which makes it the one to get unless you need something the other one does better.
Still deciding? The full Headphones rankings cover every ranked option.
Specifications Side By Side
| Fearless Audio S6Rui | Cayin Fantasy | |
|---|---|---|
| Price | $389.00 | $399.00 |
| Ranked | #372 of 450 in In-Ear Headphones | #395 of 450 in In-Ear Headphones |
| Form Factor | In-ear | In-ear |
| Back | Closed | Closed |
| Harman Preference Score | 65 (measured by crinacle, via AutoEQ) | 61 (measured by crinacle, via AutoEQ) |
| Deviation From Target | 2.70 dB standard deviation | 3.04 dB standard deviation |
| Tonal Tilt | -0.55 (negative is warmer, positive brighter) | +1.05 (negative is warmer, positive brighter) |
| Connection | Wired | Wired |
| Driver Type | Balanced armature | Dynamic |
| Drivers | 6 x balanced armature | 1 x 10.3mm dynamic |
| Impedance | 20 ohms | 37 ohms |
| Sensitivity | 113 dB | 108 dB |
| Frequency Response | 15Hz - 20kHz (Manufacturer specified) | 20Hz - 40kHz (Manufacturer specified) |
| Built-in Microphone | No | No |
| Sub-bass Extension | - | Within 6 dB of target down to 20 Hz (-4.7 dB at 30 Hz) |
Related Headphone Comparisons
More worthwhile head-to-heads for Fearless Audio S6Rui:
- Fearless Audio S8F vs Fearless Audio S6Rui
- Fearless Audio S6Rui vs FiiO FH7S
- Cayin Fantasy vs Jabra Evolve 75e
- Cayin Fantasy vs HiBy Crystal 6
- Cayin Fantasy vs Etymotic ER4XR
Prices on this page were last checked October 11, 2026 at 4:59 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.
The Two Headphones In Full
Fearless Audio S6Rui: $389.00 Linsoul eBay
Pros: Six balanced armature drivers per side earn a preference score of 65 in crinacle’s measurement, a serviceable match to the Harman target. A 20 ohm impedance and 113 dB sensitivity let it reach loud levels straight from a phone or dongle. It earns the same rating as the OpenAudio Mercury for noticeably less money.
Cons: A 2.7 dB standard deviation from target points to an uneven response that benefits from some EQ. The Fearless Audio S8F from the same maker rates higher for a modest step up in price.
Full Fearless Audio S6Rui review and specifications →
| Back | Closed |
|---|---|
| Built-in Microphone | No |
| Connection | Wired |
| Deviation From Target | 2.70 dB standard deviation |
| Driver Type | Balanced armature |
| Drivers | 6 x balanced armature |
| Form Factor | In-ear |
| Frequency Response | 15Hz - 20kHz (Manufacturer specified) |
| Harman Preference Score | 65 (measured by crinacle, via AutoEQ) |
| Impedance | 20 ohms |
| Sensitivity | 113 dB |
| Tonal Tilt | -0.55 (negative is warmer, positive brighter) |
EQ preset to match the Harman target
Set a preamp of -6.5 dB, then add these filters in any parametric equalizer (Wavelet, Equalizer APO, Peace, or a player with parametric EQ). Calculated by AutoEQ from its measured frequency response.
| Filter | Frequency | Gain | Q |
|---|---|---|---|
| Low shelf | 105 Hz | +1.8 dB | 0.70 |
| Peak | 166 Hz | -4.4 dB | 0.48 |
| Peak | 851 Hz | +3.4 dB | 1.06 |
| Peak | 2,720 Hz | +2.4 dB | 3.00 |
| Peak | 1,770 Hz | -1.3 dB | 2.18 |
| High shelf | 10,000 Hz | +6.5 dB | 0.70 |
| Peak | 5,650 Hz | +6.2 dB | 2.53 |
| Peak | 4,718 Hz | -4.5 dB | 3.03 |
| Peak | 8,599 Hz | +3.3 dB | 2.26 |
| Peak | 3,846 Hz | -1.8 dB | 6.00 |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
Cayin Fantasy: $399.00 HiFiGo eBay
Pros: Its single 10.3mm dynamic driver at 37 ohms and 108 dB runs from a phone without strain. Listeners who want a bright, detail-forward presentation will find treble well above target, and it costs less than the equally rated Fatfreq Reference Pro SE.
Cons: Crinacle’s measurement gives it a preference score of only 61.0, and squig.link hobbyist measurements show treble about 5.5 dB hot with a 12.4 dB peak near 11.2 kHz, so cymbals and sibilance can turn harsh. Sub-bass sits about 3.8 dB below target, leaving the low end thin.
Full Cayin Fantasy review and specifications →
| Back | Closed |
|---|---|
| Built-in Microphone | No |
| Connection | Wired |
| Deviation From Target | 3.04 dB standard deviation |
| Driver Type | Dynamic |
| Drivers | 1 x 10.3mm dynamic |
| Form Factor | In-ear |
| Frequency Response | 20Hz - 40kHz (Manufacturer specified) |
| Harman Preference Score | 61 (measured by crinacle, via AutoEQ) |
| Impedance | 37 ohms |
| Sensitivity | 108 dB |
| Sub-bass Extension | Within 6 dB of target down to 20 Hz (-4.7 dB at 30 Hz) |
| Tonal Tilt | +1.05 (negative is warmer, positive brighter) |
EQ preset to match the Harman target
Set a preamp of -6.4 dB, then add these filters in any parametric equalizer (Wavelet, Equalizer APO, Peace, or a player with parametric EQ). Calculated by AutoEQ from its measured frequency response.
| Filter | Frequency | Gain | Q |
|---|---|---|---|
| Low shelf | 105 Hz | +7.7 dB | 0.70 |
| Peak | 767 Hz | +3.8 dB | 0.87 |
| Peak | 77 Hz | -3.3 dB | 0.34 |
| Peak | 5,276 Hz | -7.3 dB | 5.21 |
| Peak | 2,652 Hz | -3.2 dB | 3.85 |
| High shelf | 10,000 Hz | -2.9 dB | 0.70 |
| Peak | 3,867 Hz | +1.2 dB | 4.18 |
| Peak | 7,406 Hz | -1.6 dB | 6.00 |
| Peak | 6,488 Hz | +1.3 dB | 6.00 |
| Peak | 1,421 Hz | -0.3 dB | 3.75 |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons