Short answer: the HIFIMAN RE400, though neither ranks well in its class. It ranks #397 of 450 in-ear headphones by sound quality, rated 2.9/5, at $19.99; the KZ ZEX ranks #404, rated 2.8/5, and costs $28.99, which makes this an easy call rather than a real tradeoff. Both are rated below 3.0/5 among the 450 in-ear headphones, and the Intuaura Reference 2019, ranked #5 at $34.99, is a better place to start if sound quality matters.
Why pick the HIFIMAN RE400: A very low price makes it an easy spare pair or first wired earphone. The tradeoff: Across hobbyist measurements on squig.link sub-bass sits 7.5 dB below target and falls 6 dB short by 53 Hz, while presence drops 5.8 dB and a 9.4 dB dip near 11.9 kHz dulls the top end, so music sounds lean down low and muted up high.
Why pick the KZ ZEX: It pairs a 10mm dynamic driver with a 6.8mm electrostatic driver at a low price, and its 25 ohm load suits phones and dongles. Watch for: Across 16 hobbyist measurements a 7.4 dB dip near 3.3 kHz pushes vocals back and a 6.1 dB peak near 10.2 kHz adds sizzle to cymbals, while sub-bass sits about 3.7 dB below target under 60 Hz.
Buy the HIFIMAN RE400. It is rated higher for sound quality than the KZ ZEX and costs less, so only choose the other one for a particular feature it does better.
Still deciding? The full Headphones rankings cover every ranked option.
Specifications Side By Side
| HIFIMAN RE400 | KZ ZEX | |
|---|---|---|
| Price | $19.99 | $28.99 |
| Ranked | #397 of 450 in In-Ear Headphones | #404 of 450 in In-Ear Headphones |
| Form Factor | In-ear | In-ear |
| Harman Preference Score | 60 (measured by crinacle, via AutoEQ) | 59 (measured by crinacle, via AutoEQ) |
| Deviation From Target | 3.29 dB standard deviation | 3.54 dB standard deviation |
| Tonal Tilt | +0.63 (negative is warmer, positive brighter) | -0.09 (negative is warmer, positive brighter) |
| Connection | Wired | Wired |
| Driver Type | Dynamic | Hybrid (1 dynamic + 1 electrostatic) |
| Drivers | 1 x 8.5mm dynamic | 1 x 10mm dynamic + 1 x 6.8mm electrostatic |
| Impedance | 32 ohms | 25 ohms |
| Sensitivity | 102 dB/mW | 103 dB |
| Built-in Microphone | No | - |
| Back | Closed | Closed |
| Sub-bass Extension | Falls 6 dB below target at 53 Hz (-8.0 dB at 30 Hz) | Within 6 dB of target down to 20 Hz (-4.7 dB at 30 Hz) |
| Frequency Response | - | 20Hz - 40kHz (Manufacturer specified) |
Related Headphone Comparisons
More worthwhile head-to-heads for HIFIMAN RE400:
- KZ ATE vs HIFIMAN RE400
- HIFIMAN RE400 vs KZ DQ6S
- HIFIMAN RE400 vs KZ EDX Pro
- HIFIMAN RE400 vs 1MORE Stylish
- KZ ZEX vs KZ EDX Pro
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
HIFIMAN RE400: $19.99 Amazon eBay
Pros: A very low price makes it an easy spare pair or first wired earphone. The 8.5mm dynamic driver at 32 ohms and 102 dB/mW runs fine straight from a phone or laptop. It earns the same rating as the KZ DQ6S for less money, and its balance suits listeners who prefer a neutral or lightly warm sound over heavy bass.
Cons: Across hobbyist measurements on squig.link sub-bass sits 7.5 dB below target and falls 6 dB short by 53 Hz, while presence drops 5.8 dB and a 9.4 dB dip near 11.9 kHz dulls the top end, so music sounds lean down low and muted up high. There is no built-in microphone for calls, and the KZ ATE earns a higher rating at a similar price.
Full HIFIMAN RE400 review and specifications →
| Back | Closed |
|---|---|
| Built-in Microphone | No |
| Connection | Wired |
| Deviation From Target | 3.29 dB standard deviation |
| Driver Type | Dynamic |
| Drivers | 1 x 8.5mm dynamic |
| Form Factor | In-ear |
| Harman Preference Score | 60 (measured by crinacle, via AutoEQ) |
| Impedance | 32 ohms |
| Sensitivity | 102 dB/mW |
| Sub-bass Extension | Falls 6 dB below target at 53 Hz (-8.0 dB at 30 Hz) |
| Tonal Tilt | +0.63 (negative is warmer, positive brighter) |
EQ preset to match the Harman target
Set a preamp of -6.0 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 | +6.0 dB | 0.70 |
| Peak | 3,850 Hz | +7.0 dB | 2.19 |
| Peak | 170 Hz | -2.3 dB | 0.43 |
| Peak | 2,033 Hz | -3.6 dB | 1.58 |
| Peak | 801 Hz | +1.9 dB | 1.59 |
| High shelf | 10,000 Hz | +1.7 dB | 0.70 |
| Peak | 6,033 Hz | -4.6 dB | 6.00 |
| Peak | 4,799 Hz | +2.1 dB | 4.73 |
| Peak | 3,186 Hz | +0.9 dB | 6.00 |
| Peak | 3,794 Hz | -1.0 dB | 6.00 |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
KZ ZEX: $28.99 Amazon eBay
Pros: It pairs a 10mm dynamic driver with a 6.8mm electrostatic driver at a low price, and its 25 ohm load suits phones and dongles. In squig.link measurements bass runs about 2.4 dB above target from 60 to 200 Hz, a warm, V-shaped balance for listeners who like a fuller low end. It rates above the KZ EDX Pro and Final Audio E3000.
Cons: Across 16 hobbyist measurements a 7.4 dB dip near 3.3 kHz pushes vocals back and a 6.1 dB peak near 10.2 kHz adds sizzle to cymbals, while sub-bass sits about 3.7 dB below target under 60 Hz. The KZ DQ6S rates a bit higher at the same price, and the HIFIMAN RE400 rates higher for less.
Full KZ ZEX review and specifications →
| Back | Closed |
|---|---|
| Connection | Wired |
| Deviation From Target | 3.54 dB standard deviation |
| Driver Type | Hybrid (1 dynamic + 1 electrostatic) |
| Drivers | 1 x 10mm dynamic + 1 x 6.8mm electrostatic |
| Form Factor | In-ear |
| Frequency Response | 20Hz - 40kHz (Manufacturer specified) |
| Harman Preference Score | 59 (measured by crinacle, via AutoEQ) |
| Impedance | 25 ohms |
| Sensitivity | 103 dB |
| Sub-bass Extension | Within 6 dB of target down to 20 Hz (-4.7 dB at 30 Hz) |
| Tonal Tilt | -0.09 (negative is warmer, positive brighter) |
EQ preset to match the Harman target
Set a preamp of -6.1 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 | +10.5 dB | 0.70 |
| Peak | 63 Hz | -7.6 dB | 0.22 |
| Peak | 2,608 Hz | +11.0 dB | 0.73 |
| Peak | 823 Hz | +4.4 dB | 1.11 |
| Peak | 1,854 Hz | -11.3 dB | 0.98 |
| High shelf | 10,000 Hz | -1.4 dB | 0.70 |
| Peak | 9,677 Hz | +1.8 dB | 2.53 |
| Peak | 4,715 Hz | -5.1 dB | 5.44 |
| Peak | 6,131 Hz | +3.3 dB | 5.78 |
| Peak | 3,526 Hz | +1.5 dB | 3.26 |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons