Short answer: the Audio-Technica ATH-IEX1, though neither ranks well in its class. It ranks #420 of 450 in-ear headphones by sound quality, rated 2.4/5, at $1,200. The Fidue A91 Sirius ranks #423, rated 2.3/5, at $899.99, $300.01 cheaper, a saving that is not big enough to make up the sound-quality gap. Both are rated below 3.0/5 among the 450 in-ear headphones, so if sound quality matters, consider the ThieAudio Monarch MKIII instead, ranked #1 at $999.
The case for the Audio-Technica ATH-IEX1: A hybrid design pairing two dynamic drivers with two balanced armatures, and its 102 dB/mW sensitivity makes it easy to drive from a phone. Watch for: A preference score of 54 in crinacle’s measurement places its tuning far from what most listeners prefer, a weak result for a flagship in ear.
What the Fidue A91 Sirius does well: A hybrid of one dynamic driver and four balanced armatures per side offers a multi-driver layout for listeners who want one. The tradeoff: A preference score of 53 in crinacle’s measurement places its tuning far from what most listeners prefer.
Buy the Audio-Technica ATH-IEX1. It is rated higher for sound quality, and saving $300.01 with the Fidue A91 Sirius does not make up for the sound-quality gap.
Want more options? Browse the full Headphones rankings.
Specifications Side By Side
| Audio-Technica ATH-IEX1 | Fidue A91 Sirius | |
|---|---|---|
| Price | $1,200.00 | $899.99 |
| Ranked | #420 of 450 in In-Ear Headphones | #423 of 450 in In-Ear Headphones |
| Form Factor | In-ear | In-ear |
| Back | Closed | Closed |
| Harman Preference Score | 54 (measured by crinacle, via AutoEQ) | 53 (measured by crinacle, via AutoEQ) |
| Deviation From Target | 3.30 dB standard deviation | 4.06 dB standard deviation |
| Tonal Tilt | -0.55 (negative is warmer, positive brighter) | +0.13 (negative is warmer, positive brighter) |
| Connection | Wired | Wired |
| Driver Type | Hybrid (2 dynamic + 2 balanced armature) | Hybrid (1 dynamic + 4 balanced armature) |
| Drivers | 1 x 9.8mm dynamic + 1 x 8.8mm dynamic + 2 x balanced armature | 1 x dynamic + 4 x balanced armature |
| Impedance | 5 ohms | 20 ohms |
| Sensitivity | 102 dB/mW | 113 dB |
| Frequency Response | 5Hz - 50kHz (Manufacturer specified) | 4Hz - 45kHz (Manufacturer specified) |
| Built-in Microphone | No | No |
Related Headphone Comparisons
How Audio-Technica ATH-IEX1 compares with other leading options:
- FiiO FH5 vs Audio-Technica ATH-IEX1
- Westone MACH 80 vs Audio-Technica ATH-IEX1
- Audio-Technica ATH-IEX1 vs FiiO FA7S
- Fidue A91 Sirius vs FiiO FA7S
- DUNU DK4001 vs Fidue A91 Sirius
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
Audio-Technica ATH-IEX1: $1,200.00 B&H Photo Video eBay
Pros: A hybrid design pairing two dynamic drivers with two balanced armatures, and its 102 dB/mW sensitivity makes it easy to drive from a phone. It is rated above the Fidue A91 Sirius and FiiO FA7S.
Cons: A preference score of 54 in crinacle’s measurement places its tuning far from what most listeners prefer, a weak result for a flagship in ear. The Audio-Technica ATH-CK2000Ti is rated higher and costs less.
Full Audio-Technica ATH-IEX1 review and specifications →
| Released | Nov 2019 (6 years ago) |
|---|---|
| Back | Closed |
| Built-in Microphone | No |
| Connection | Wired |
| Deviation From Target | 3.30 dB standard deviation |
| Driver Type | Hybrid (2 dynamic + 2 balanced armature) |
| Drivers | 1 x 9.8mm dynamic + 1 x 8.8mm dynamic + 2 x balanced armature |
| Form Factor | In-ear |
| Frequency Response | 5Hz - 50kHz (Manufacturer specified) |
| Harman Preference Score | 54 (measured by crinacle, via AutoEQ) |
| Impedance | 5 ohms |
| Sensitivity | 102 dB/mW |
| Tonal Tilt | -0.55 (negative is warmer, positive brighter) |
EQ preset to match the Harman target
Set a preamp of -6.9 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 | -2.4 dB | 0.70 |
| Peak | 641 Hz | +5.0 dB | 1.22 |
| Peak | 1,454 Hz | -7.5 dB | 1.77 |
| Peak | 5,117 Hz | +7.4 dB | 1.56 |
| Peak | 3,198 Hz | -6.2 dB | 3.37 |
| High shelf | 10,000 Hz | +0.8 dB | 0.70 |
| Peak | 154 Hz | -2.2 dB | 1.07 |
| Peak | 67 Hz | +1.0 dB | 1.34 |
| Peak | 373 Hz | +1.2 dB | 2.14 |
| Peak | 6,320 Hz | +0.9 dB | 6.00 |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
Fidue A91 Sirius: $899.99 Amazon eBay
Pros: A hybrid of one dynamic driver and four balanced armatures per side offers a multi-driver layout for listeners who want one. Its rating sits above the FiiO FA7S, which costs slightly more. No amp is needed, since the 113 dB sensitivity gives plenty of volume from a phone.
Cons: A preference score of 53 in crinacle’s measurement places its tuning far from what most listeners prefer. The Kinera Skuld and Audio-Technica ATH-CK2000Ti are both rated higher and cost noticeably less, and there is no microphone for calls.
Full Fidue A91 Sirius review and specifications →
| Released | Jun 2016 (10 years ago) |
|---|---|
| Back | Closed |
| Built-in Microphone | No |
| Connection | Wired |
| Deviation From Target | 4.06 dB standard deviation |
| Driver Type | Hybrid (1 dynamic + 4 balanced armature) |
| Drivers | 1 x dynamic + 4 x balanced armature |
| Form Factor | In-ear |
| Frequency Response | 4Hz - 45kHz (Manufacturer specified) |
| Harman Preference Score | 53 (measured by crinacle, via AutoEQ) |
| Impedance | 20 ohms |
| Sensitivity | 113 dB |
| Tonal Tilt | +0.13 (negative is warmer, positive brighter) |
EQ preset to match the Harman target
Set a preamp of -7.3 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 | +5.5 dB | 0.70 |
| Peak | 9,827 Hz | +5.4 dB | 1.70 |
| Peak | 168 Hz | -4.0 dB | 0.65 |
| Peak | 4,982 Hz | +5.4 dB | 1.22 |
| Peak | 1,608 Hz | -6.0 dB | 3.14 |
| High shelf | 10,000 Hz | +4.6 dB | 0.70 |
| Peak | 859 Hz | +3.0 dB | 1.73 |
| Peak | 331 Hz | -1.0 dB | 1.86 |
| Peak | 1,257 Hz | -2.3 dB | 3.72 |
| Peak | 9,483 Hz | -2.7 dB | 4.60 |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons