Short answer: the IOAudio Sogno. It ranks #3 of 450 in-ear headphones by sound quality, rated 4.9/5, at $399. The EPZ K9 ranks #34, rated 4.7/5, at $349.99, $49.01 cheaper, a saving that is not big enough to make up the sound-quality gap.
What the IOAudio Sogno does well: Its preference score of 88, taken from the median of six hobbyist measurements, comes with an average deviation of only about 0.8 dB, one of the most even responses among in-ears. The tradeoff: A 3.3 dB dip near 6.5 kHz next to a 3.6 dB peak near 8.1 kHz can make some cymbals and sibilants sound slightly uneven.
What the EPZ K9 does well: In the median of 19 hobbyist measurements on squig.link, the K9 earns a preference score of 82 with a low 1.26 dB deviation, so its eight balanced armatures and dynamic woofer blend into a cohesive, gently warm tuning. Watch for: Air above 10 kHz runs about 3.4 dB above target and a 4 dB peak sits near 8.1 kHz, which can add a slightly bright edge to cymbals.
Buy the IOAudio Sogno. It is rated higher for sound quality, and the $49.01 you would save on the EPZ K9 does not close the gap.
Looking for alternatives? See the complete Headphones rankings.
Specifications Side By Side
| IOAudio Sogno | EPZ K9 | |
|---|---|---|
| Price | $399.00 | $349.99 |
| Ranked | #3 of 450 in In-Ear Headphones | #34 of 450 in In-Ear Headphones |
| Form Factor | In-ear | In-ear |
| Back | Closed | Closed |
| Harman Preference Score | 88 (median of 6 squig.link measurements, calibrated to AutoEQ) | 82 (median of 20 squig.link measurements, calibrated to AutoEQ) |
| Deviation From Target | 0.84 dB standard deviation | 1.25 dB standard deviation |
| Tonal Tilt | -0.07 (negative is warmer, positive brighter) | -0.15 (negative is warmer, positive brighter) |
| Sub-bass Extension | Within 6 dB of target down to 20 Hz (+0.2 dB at 30 Hz) | Within 6 dB of target down to 20 Hz (-1.2 dB at 30 Hz) |
| Connection | Wired | Wired |
| Driver Type | Hybrid (2 dynamic + 6 balanced armature) | Hybrid (1 dynamic + 8 balanced armature) |
| Drivers | 1 x 10mm + 6mm coaxial dual dynamic + 6 x balanced armature | 1 x dynamic + 8 x balanced armature |
| Impedance | 12.8 ohms | 14 ohms |
| Sensitivity | 126.5 dB/Vrms | 108 dB |
| Frequency Response | 10Hz - 30kHz (Manufacturer specified) | - |
| Built-in Microphone | No | - |
Related Headphone Comparisons
How IOAudio Sogno compares with other leading options:
- AKG N5005 vs IOAudio Sogno
- IOAudio Sogno vs Moondrop Harmon
- EPZ K9 vs Moondrop Harmon
- EPZ K9 vs Inawaken Twilight-DS
- EPZ K9 vs Tanchjim Soda
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
IOAudio Sogno: $399.00 Amazon eBay
Pros: Its preference score of 88, taken from the median of six hobbyist measurements, comes with an average deviation of only about 0.8 dB, one of the most even responses among in-ears. Every broad band from sub-bass to air lands within about 1.3 dB of the Harman target, so bass, vocals and treble all sit in natural proportion. A coaxial dual dynamic woofer with six balanced armatures at 126.5 dB/Vrms plays loudly from a phone. It is rated above the Moondrop Harmon and Tanchjim Soda at a similar price.
Cons: A 3.3 dB dip near 6.5 kHz next to a 3.6 dB peak near 8.1 kHz can make some cymbals and sibilants sound slightly uneven. Only six samples were measured, so unit to unit variation is less well established, and the sensitivity is high enough that noisy sources may hiss. It has no built-in microphone.
Full IOAudio Sogno review and specifications →
| Back | Closed |
|---|---|
| Built-in Microphone | No |
| Connection | Wired |
| Deviation From Target | 0.84 dB standard deviation |
| Driver Type | Hybrid (2 dynamic + 6 balanced armature) |
| Drivers | 1 x 10mm + 6mm coaxial dual dynamic + 6 x balanced armature |
| Form Factor | In-ear |
| Frequency Response | 10Hz - 30kHz (Manufacturer specified) |
| Harman Preference Score | 88 (median of 6 squig.link measurements, calibrated to AutoEQ) |
| Impedance | 12.8 ohms |
| Sensitivity | 126.5 dB/Vrms |
| Sub-bass Extension | Within 6 dB of target down to 20 Hz (+0.2 dB at 30 Hz) |
| Tonal Tilt | -0.07 (negative is warmer, positive brighter) |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
EPZ K9: $349.99 Amazon eBay
Pros: In the median of 19 hobbyist measurements on squig.link, the K9 earns a preference score of 82 with a low 1.26 dB deviation, so its eight balanced armatures and dynamic woofer blend into a cohesive, gently warm tuning. Sub-bass is within half a decibel of target and bass about 1.9 dB above it, giving a full low end without boom. The 14 ohm, 108 dB sensitivity rating means it plays loud from a phone.
Cons: Air above 10 kHz runs about 3.4 dB above target and a 4 dB peak sits near 8.1 kHz, which can add a slightly bright edge to cymbals. It is rated below the similarly priced AKG N5005 and IOAudio Sogno, which makes it a harder sell at this price. The very low 14 ohm impedance can make the tuning shift on sources with high output impedance.
Full EPZ K9 review and specifications →
| Back | Closed |
|---|---|
| Connection | Wired |
| Deviation From Target | 1.25 dB standard deviation |
| Driver Type | Hybrid (1 dynamic + 8 balanced armature) |
| Drivers | 1 x dynamic + 8 x balanced armature |
| Form Factor | In-ear |
| Harman Preference Score | 82 (median of 20 squig.link measurements, calibrated to AutoEQ) |
| Impedance | 14 ohms |
| Sensitivity | 108 dB |
| Sub-bass Extension | Within 6 dB of target down to 20 Hz (-1.2 dB at 30 Hz) |
| Tonal Tilt | -0.15 (negative is warmer, positive brighter) |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons