Short answer: a tie on sound quality. Both are rated 4.4/5 (#173 and #139 of 1291 in-ear headphones) at nearly the same price ($396 vs $399), so choose on features and fit.
What the HeartField CU8 does well: Four balanced armatures produce one of the smoothest responses at this level, deviating only 1.4 dB on average from target in squig.link hobbyist measurements, for a preference score of 78. The tradeoff: Treble is reserved, with presence about 2 dB down, a 4 dB dip near 9.5 kHz and air 3.3 dB below target, so cymbals and vocal sparkle sound a little muted.
The case for the Unique Melody 3DT: Four hobbyist measurements on squig.link give the 3DT a preference score of 79.0, with its three dynamic drivers producing a balanced response where every band from 60 Hz to 10 kHz sits within 1.6 dB of target. The catch: A 7 dB peak near 8 kHz adds an edge to cymbals and sibilance that some listeners will find fatiguing.
Buy the HeartField CU8 or the Unique Melody 3DT on features: they are rated the same for sound quality at close to the same price.
Looking for alternatives? See the complete Headphones rankings.
Four balanced armatures produce one of the smoothest responses at this level, deviating only 1.4 dB on average from target in squig.link hobbyist measurements, for a preference score of 78.
Linsoul $396.00 eBay
Four hobbyist measurements on squig.link give the 3DT a preference score of 79.0, with its three dynamic drivers producing a balanced response where every band from 60 Hz to 10 kHz sits within 1.6 dB of target.
Linsoul $399.00 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
| HeartField CU8 | Unique Melody 3DT | |
|---|---|---|
| Price | $396.00 | $399.00 |
| Ranked | #173 of 1291 in In-Ear Headphones | #139 of 1291 in In-Ear Headphones |
| Form Factor | In-ear | In-ear |
| Back | Closed | Closed |
| Harman Preference Score | 78 (median of 6 squig.link measurements, calibrated to AutoEQ) | 79 (median of 4 squig.link measurements, calibrated to AutoEQ) |
| Deviation From Target | 1.39 dB standard deviation | 1.60 dB standard deviation |
| Tonal Tilt | -0.62 (negative is warmer, positive brighter) | +0.18 (negative is warmer, positive brighter) |
| Sub-bass Extension | Within 6 dB of target down to 20 Hz (+2.2 dB at 30 Hz) | Within 6 dB of target down to 20 Hz (-1.4 dB at 30 Hz) |
| Connection | Wired | Wired |
| Driver Type | Balanced armature | Dynamic |
| Drivers | 4 x balanced armature | 2 x 7mm dynamic + 1 x 10mm dynamic |
| Impedance | 17 ohms | 25.4 ohms |
| Sensitivity | 108 dB | 113 dB |
| Frequency Response | 10Hz - 20kHz (Manufacturer specified) | 20Hz - 20kHz (Manufacturer specified) |
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 HeartField CU8 from audioamigo, hbb, jaytiss, pw, soundcheck39 and timmyv; the Unique Melody 3DT from dl, precog, tgx78 and timmyv, all via squig.link.
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