Short answer: the EPZ x Tipsy Star One. Both are rated 4.2/5 for sound quality (#277 and #260 of 1291 in-ear headphones), and the EPZ x Tipsy Star One costs $86.59 against $99.99 for the Fosi Audio IM4, and with sound quality even, the cheaper one is the better buy.
What the EPZ x Tipsy Star One does well: The median of 12 hobbyist measurements gives it a very good Harman preference score of 76 with a 1.68 dB spread. The tradeoff: Its 1.68 dB spread is less even than the best measured sets.
The case for the Fosi Audio IM4: The median of 18 hobbyist measurements gives it a very good Harman preference score of 76 with a 1.77 dB spread, and its mids sit within about 1.2 dB of target, so vocals and instruments sound natural. Watch for: A 4.6 dB peak near 8.2 kHz can make cymbals and sibilance sound sharp.
Buy the EPZ x Tipsy Star One. Both are rated the same for sound quality, and it costs $13.40 less than the Fosi Audio IM4.
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The median of 12 hobbyist measurements gives it a very good Harman preference score of 76 with a 1.68 dB spread.
Amazon $86.59 eBay
The median of 18 hobbyist measurements gives it a very good Harman preference score of 76 with a 1.77 dB spread, and its mids sit within about 1.2 dB of target, so vocals and instruments sound natural.
Amazon $99.99 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 x Tipsy Star One | Fosi Audio IM4 | |
|---|---|---|
| Price | $86.59 | $99.99 |
| Ranked | #277 of 1291 in In-Ear Headphones | #260 of 1291 in In-Ear Headphones |
| Form Factor | In-ear | In-ear |
| Back | Closed | Closed |
| Harman Preference Score | 76 (median of 12 squig.link measurements, calibrated to AutoEQ) | 76 (median of 18 squig.link measurements, calibrated to AutoEQ) |
| Deviation From Target | 1.68 dB standard deviation | 1.77 dB standard deviation |
| Tonal Tilt | -0.41 (negative is warmer, positive brighter) | -0.23 (negative is warmer, positive brighter) |
| Sub-bass Extension | Within 6 dB of target down to 20 Hz (+0.6 dB at 30 Hz) | Within 6 dB of target down to 20 Hz (-0.7 dB at 30 Hz) |
| Connection | Wired | Wired |
| Driver Type | Dynamic | Dynamic |
| Drivers | 1 x 10mm dynamic | 1 x 10mm dynamic |
| Impedance | 64 ohms | 21 ohms |
| Sensitivity | 112 dB | 109 dB |
| Frequency Response | 20Hz - 40kHz (Manufacturer specified) | 20Hz - 20kHz (Manufacturer specified) |
| Weight | - | 0 lbs (7 g) per earbud |
| 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 x Tipsy Star One from aftersound, ankramutt, digaoreviews, jaytiss, mmagtech, musicafe, pw, regancipher, soundignity, suporsalad, tonedeafmonk and vortexreviews; the Fosi Audio IM4 from atechreviews, audioamigo, boizoff, digaoreviews, elrics, hu-fi, jaytiss, joycesreview, musicafe, practiphile, pw, samreviews, soundcheck39, soundignity, superreview, theaudiostore, tonedeafmonk and treblewellxtended, all via squig.link.
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