Short answer: a tie on sound quality. Both are rated 4.3/5 (#219 and #184 of 1291 in-ear headphones) at nearly the same price ($59 vs $55.99), so choose on features and fit.
What the EPZ K5 does well: The median of 11 hobbyist measurements gives it a very good Harman preference score of 77 with a 1.68 dB spread, and its mids sit within about 0.5 dB of target, so vocals and instruments sound natural. Watch for: A 6.1 dB peak near 8.2 kHz can make cymbals and sibilance sound sharp.
What the KZ ZEX Pro does well: The median of 20 hobbyist measurements gives it a very good Harman preference score of 78 with a 1.60 dB spread. Watch for: Presence sits about 3.2 dB low with a 6.6 dB dip near 11.9 kHz, so vocals and instruments lose some bite.
Buy the EPZ K5 or the KZ ZEX Pro on features: they are rated the same for sound quality at close to the same price.
Still deciding? The full Headphones rankings cover every ranked option.
The median of 11 hobbyist measurements gives it a very good Harman preference score of 77 with a 1.68 dB spread, and its mids sit within about 0.5 dB of target, so vocals and instruments sound natural.
Amazon $59.00 eBay
The median of 20 hobbyist measurements gives it a very good Harman preference score of 78 with a 1.60 dB spread.
Amazon $55.99 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
| EPZ K5 | KZ ZEX Pro | |
|---|---|---|
| Price | $59.00 | $55.99 |
| Ranked | #219 of 1291 in In-Ear Headphones | #184 of 1291 in In-Ear Headphones |
| Form Factor | In-ear | In-ear |
| Back | Closed | Closed |
| Harman Preference Score | 77 (median of 11 squig.link measurements, calibrated to AutoEQ) | 78 (median of 20 squig.link measurements, calibrated to AutoEQ) |
| Deviation From Target | 1.68 dB standard deviation | 1.60 dB standard deviation |
| Tonal Tilt | +0.27 (negative is warmer, positive brighter) | -0.27 (negative is warmer, positive brighter) |
| Sub-bass Extension | Within 6 dB of target down to 20 Hz (-2.3 dB at 30 Hz) | Within 6 dB of target down to 20 Hz (-0.6 dB at 30 Hz) |
| Connection | Wired | Wired |
| Driver Type | Hybrid (1 dynamic + 4 balanced armature) | Hybrid (1 dynamic + 1 balanced armature + 1 electrostatic) |
| Drivers | 1 x 8mm dynamic + 4 x balanced armature | 1 x 10mm dynamic + 1 x balanced armature + 1 x electrostatic |
| Impedance | 30 ohms | 25 ohms |
| Sensitivity | 114 dB/mW | 104 dB |
| Frequency Response | 20Hz - 20kHz (Manufacturer specified) | 20Hz - 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 EPZ K5 from aftersound, cammyfi, dl, fahryst, hbb, kuping-sensi, mmagtech, pw, soundcheck39, superreview and tonedeafmonk; the KZ ZEX Pro from achoreviews, aftersound, ankramutt, bassyalexander, boizoff, dchpgall, dentreviews, eplv, filk, flare, hbb, ianfann, jacstone, loomynarty, lown-fi, precog, recode, rg, tgx78 and vortexreviews, all via squig.link.
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