Short answer: the Symphonium Audio Helios. It ranks #64 of 450 in-ear headphones by sound quality, rated 4.5/5, at $1,099. The Letshuoer Mystic 8 ranks #169, rated 4.3/5, at $989, $110 cheaper, a saving that is not big enough to make up the sound-quality gap.
Why pick the Symphonium Audio Helios: One of the smoothest in-ears measured, with a 1.57 dB standard deviation from the Harman target and a preference score of 80. Watch for: The presence region from 3 to 6 kHz sits 3.5 dB below target, with a 6.3 dB dip near 6.95 kHz, so vocals and guitars lose a little bite and detail.
Buy the Symphonium Audio Helios. It is rated higher for sound quality, and the $110 saving on the Letshuoer Mystic 8 is not enough to make up the difference.
Looking for alternatives? See the complete Headphones rankings.
Specifications Side By Side
| Symphonium Audio Helios | Letshuoer Mystic 8 | |
|---|---|---|
| Price | $1,099.00 | $989.00 |
| Ranked | #64 of 450 in In-Ear Headphones | #169 of 450 in In-Ear Headphones |
| Form Factor | In-ear | In-ear |
| Back | Closed | Closed |
| Harman Preference Score | 80 (measured by HypetheSonics, via AutoEQ) | 77 (median of 21 squig.link measurements, calibrated to AutoEQ) |
| Deviation From Target | 1.57 dB standard deviation | 1.66 dB standard deviation |
| Tonal Tilt | +0.02 (negative is warmer, positive brighter) | +0.10 (negative is warmer, positive brighter) |
| Sub-bass Extension | Within 6 dB of target down to 20 Hz (-1.3 dB at 30 Hz) | Within 6 dB of target down to 20 Hz (-2.9 dB at 30 Hz) |
| Connection | Wired | Wired |
| Driver Type | Balanced armature | Balanced armature |
| Impedance | 8.5 ohms | 18 ohms |
| Sensitivity | 104 dB/Vrms | 107 dB |
| Frequency Response | 12Hz - 24kHz (Manufacturer specified) | 20Hz - 40kHz (Manufacturer specified) |
| Built-in Microphone | No | - |
| Drivers | - | 8 x balanced armature |
Related Headphone Comparisons
More top alternatives to Symphonium Audio Helios:
- ThieAudio Monarch MKIII vs Symphonium Audio Helios
- Simgot EM6L vs Symphonium Audio Helios
- Symphonium Audio Helios vs ThieAudio Monarch MKIV
- Symphonium Audio Helios vs DUNU Glacier
- ThieAudio Monarch MKIV vs Letshuoer Mystic 8
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.
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The Two Headphones In Full
Symphonium Audio Helios: $1,099.00 Headphones.com eBay
Pros: One of the smoothest in-ears measured, with a 1.57 dB standard deviation from the Harman target and a preference score of 80. Bass reaches all the way down, sitting only 1.3 dB under target at 30 Hz, so kick drums and synth bass keep their rumble from an all balanced armature design. Overall tilt is essentially flat, and listeners who like a warm, bass-forward balance are the best match. It earns a higher rating than the SoftEars Twilight and the HIFIMAN RE2000.
Cons: The presence region from 3 to 6 kHz sits 3.5 dB below target, with a 6.3 dB dip near 6.95 kHz, so vocals and guitars lose a little bite and detail. The ThieAudio Monarch MKIII costs about the same and carries a higher rating.
Full Symphonium Audio Helios review and specifications →
| Released | 2021 (5 years ago) |
|---|---|
| Back | Closed |
| Built-in Microphone | No |
| Connection | Wired |
| Deviation From Target | 1.57 dB standard deviation |
| Driver Type | Balanced armature |
| Form Factor | In-ear |
| Frequency Response | 12Hz - 24kHz (Manufacturer specified) |
| Harman Preference Score | 80 (measured by HypetheSonics, via AutoEQ) |
| Impedance | 8.5 ohms |
| Sensitivity | 104 dB/Vrms |
| Sub-bass Extension | Within 6 dB of target down to 20 Hz (-1.3 dB at 30 Hz) |
| Tonal Tilt | +0.02 (negative is warmer, positive brighter) |
EQ preset to match the Harman target
Set a preamp of -2.8 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 | -2.6 dB | 0.70 |
| Peak | 1,245 Hz | -1.7 dB | 0.50 |
| Peak | 71 Hz | +3.6 dB | 0.56 |
| Peak | 6,561 Hz | +3.7 dB | 4.67 |
| Peak | 3,355 Hz | +2.2 dB | 2.99 |
| High shelf | 10,000 Hz | -7.3 dB | 0.70 |
| Peak | 276 Hz | +0.5 dB | 1.70 |
| Peak | 533 Hz | -0.4 dB | 2.28 |
| Peak | 4,907 Hz | +1.5 dB | 6.00 |
| Peak | 139 Hz | -0.3 dB | 2.01 |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
Letshuoer Mystic 8: $989.00 Linsoul eBay
Full Letshuoer Mystic 8 review and specifications →
| Released | Feb 2025 (1 year ago) |
|---|---|
| Back | Closed |
| Connection | Wired |
| Deviation From Target | 1.66 dB standard deviation |
| Driver Type | Balanced armature |
| Drivers | 8 x balanced armature |
| Form Factor | In-ear |
| Frequency Response | 20Hz - 40kHz (Manufacturer specified) |
| Harman Preference Score | 77 (median of 21 squig.link measurements, calibrated to AutoEQ) |
| Impedance | 18 ohms |
| Sensitivity | 107 dB |
| Sub-bass Extension | Within 6 dB of target down to 20 Hz (-2.9 dB at 30 Hz) |
| Tonal Tilt | +0.10 (negative is warmer, positive brighter) |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons