Short answer: the LZ A4 Pro. It ranks #1002 of 1369 in-ear headphones by sound quality, rated 3.2/5, at $246.05. The FatFreq x HBB Deuce ranks #1078, rated 3.0/5, at $239, $7.05 cheaper, which does not close the gap in sound quality.
Why pick the LZ A4 Pro: A published AutoEQ preset corrects its response toward the Harman target, so a few minutes of EQ setup closes most of the gap. Watch for: Treble about 5 dB below target from 3 to 10 kHz, which can sound dull or veiled next to brighter headphones.
Why pick the FatFreq x HBB Deuce: Lower mids sit within about 0.5 dB of target, keeping voices and guitars natural. The catch: A Harman score of 61 places it in the lower part of the in-ear rankings.
Buy the LZ A4 Pro. It is rated higher for sound quality, and the $7.05 you would save on the FatFreq x HBB Deuce does not close the gap.
Still deciding? The full Headphones rankings cover every ranked option.
A published AutoEQ preset corrects its response toward the Harman target, so a few minutes of EQ setup closes most of the gap.
HiFiGo $246.05 eBay
Lower mids sit within about 0.5 dB of target, keeping voices and guitars natural.
Bloom Audio $239.00 eBayPrices on this page were last checked October 17, 2026 at 6:04 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
| LZ A4 Pro | FatFreq x HBB Deuce | |
|---|---|---|
| Price | $246.05 | $239.00 |
| Ranked | #1002 of 1369 in In-Ear Headphones | #1078 of 1369 in In-Ear Headphones |
| Form Factor | In-ear | In-ear |
| Back | Closed | Closed |
| Harman Preference Score | 64 (median of 3 squig.link measurements, calibrated to AutoEQ) | 61 (median of 22 squig.link measurements, calibrated to AutoEQ) |
| Deviation From Target | 2.97 dB standard deviation | 2.82 dB standard deviation |
| Tonal Tilt | -0.47 (negative is warmer, positive brighter) | -1.30 (negative is warmer, positive brighter) |
| Sub-bass Extension | Within 6 dB of target down to 20 Hz (-0.9 dB at 30 Hz) | Within 6 dB of target down to 20 Hz (+6.3 dB at 30 Hz) |
| Connection | Wired | Wired |
| Driver Type | Hybrid (1 dynamic + 3 balanced armature) | Dynamic |
| Drivers | 1 x CNT dynamic driver + 3 x Knowles balanced armature drivers | 2 x dynamic |
| Impedance | 26 ohms | - |
| Sensitivity | 112 dB/mW | - |
| Frequency Response | 20Hz - 20kHz | - |
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 LZ A4 Pro from achoreviews, ankramutt and rg; the FatFreq x HBB Deuce from aden, adri-n, aftersound, audioamigo, bassaudio, bassyalexander, bloomaudio, ducbloke, eliseaudio, harutohiroki, hobbytalk, jaytiss, joycesreview, koi, kr0mka, pw, sl0the, soundignity, superreview, theaudiostore, therollo9 and tonedeafmonk, all via squig.link.
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