Short answer: a tie on sound quality. Both are rated 3.2/5 (#957 and #954 of 1291 in-ear headphones) at nearly the same price ($199.99 vs $199), so choose on features and fit.
What the DUNU x KOTO ITO does well: Bass is boosted about 4 dB across both sub-bass and mid-bass, and it holds that level all the way down to 20 Hz, so electronic and hip-hop tracks get real weight and rumble. Watch for: A Harman preference score of 64.4 in hobbyist measurements reflects a tilted, bass-heavy tuning that will feel thick to listeners who want neutral sound.
The case for the NF Acous NM25: A single dynamic driver earphone with a bright, detailed character that suits V-shaped and neutral listeners, with a low end that stays within 6 dB of target down to 20 Hz. The catch: Treble runs about 6 dB above target from 6 to 16 kHz, peaking 12.3 dB near 11.2 kHz in the median of 7 hobbyist measurements on squig.link, so cymbals, hi-hats and sibilance can sound hot and fatiguing at higher volume.
Buy the DUNU x KOTO ITO or the NF Acous NM25 on features: they are rated the same for sound quality at close to the same price.
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Bass is boosted about 4 dB across both sub-bass and mid-bass, and it holds that level all the way down to 20 Hz, so electronic and hip-hop tracks get real weight and rumble.
Amazon $199.99 eBay
A single dynamic driver earphone with a bright, detailed character that suits V-shaped and neutral listeners, with a low end that stays within 6 dB of target down to 20 Hz.
Amazon $199.00 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 x KOTO ITO | NF Acous NM25 | |
|---|---|---|
| Price | $199.99 | $199.00 |
| Ranked | #957 of 1291 in In-Ear Headphones | #954 of 1291 in In-Ear Headphones |
| Form Factor | In-ear | In-ear |
| Back | Closed | Closed |
| Harman Preference Score | 64 (median of 8 squig.link measurements, calibrated to AutoEQ) | 64 (median of 7 squig.link measurements, calibrated to AutoEQ) |
| Deviation From Target | 2.37 dB standard deviation | 2.42 dB standard deviation |
| Tonal Tilt | -1.12 (negative is warmer, positive brighter) | +0.93 (negative is warmer, positive brighter) |
| Sub-bass Extension | Within 6 dB of target down to 20 Hz (+4.0 dB at 30 Hz) | Within 6 dB of target down to 20 Hz (-1.5 dB at 30 Hz) |
| Connection | Wired | Wired |
| Driver Type | Hybrid (2 dynamic + 2 balanced armature) | Dynamic |
| Drivers | 1 x 10mm dynamic + 1 x 8mm dynamic + 2 x balanced armature | 1 x dynamic |
| Impedance | 37 ohms | 32 ohms |
| Sensitivity | 105 dB/mW | 108 dB/mW |
| Weight | 0 lbs (6.5 g) per side | - |
| 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 x KOTO ITO from atechreviews, audioamigo, bassaudio, elrics, hobbytalk, jaytiss, soundignity and tonedeafmonk; the NF Acous NM25 from cqtek, digaoreviews, faxepremium, musicafe, practiphile, pw, tonedeafmonk and treblewellxtended, all via squig.link.
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