The EPZ Star One is 64Ω with a sensitivity of 100.1 dB/mW, which is 112.0 dB/V. To reach 100 dB SPL — genuinely loud, louder than most people listen — it needs 0.98 mW, or 0.25 V across the drivers.
That puts it in the easy category. A phone, a laptop headphone jack or the cheapest USB dongle will drive it to painful levels. Of the 280 sources in the database, 277 have at least 10 dB of headroom and another 3 have enough. The cheapest portable source that does the job is the Apple USB-C dongle (US) at $9.
Sensitivity here is in dB per milliwatt. Why the unit matters.
EPZ publishes this as 112 dB/Vrms (@1kHz) — a figure per volt, not per milliwatt. At 64Ω the two differ by 11.9 dB, so the 100.1 dB/mW above is that published number converted, not a different measurement.
This is the conversion that online calculators skip. Quote the per-volt number as if it were per-milliwatt and this headphone looks 12 dB easier to drive than it is — which is roughly the difference between a dongle being enough and not being enough.
EPZ prints the impedance as 64Ω (±15%) @1kHz, not as a bare number. Everything on this page is calculated with the nominal 64Ω, and the rest of that line is quoted here rather than tidied away, because how a figure is qualified is part of the specification too.
Source: epzaudio.com. How this data was built.
| As it is labelled | As printed | Tolerance | Standard |
|---|---|---|---|
| Frequency Response | 20Hz - 40kHz | not printed | not printed |
EPZ prints 20Hz - 40kHz for the EPZ Star One, under the heading “Frequency Response”. Source: epzaudio.com.
No tolerance is printed with it, so “20Hz - 40kHz” says nothing about how loud this headphone actually is at 20 Hz.
Only what the maker printed; maker by maker.
| Level | What it is | Power | Voltage | Current |
|---|---|---|---|---|
| 85 dB SPL | quiet background listening | 0.03 mW | 44 mV | 0.7 mA |
| 95 dB SPL | normal listening | 0.31 mW | 0.14 V | 2.2 mA |
| 100 dB SPL | loud listening | 0.98 mW | 0.25 V | 3.9 mA |
| 105 dB SPL | very loud | 3.1 mW | 0.44 V | 6.9 mA |
| 110 dB SPL | peaks on dynamic music | 9.8 mW | 0.79 V | 12.4 mA |
Most people listen between 75 and 85 dB; the 100 dB row leaves room for peaks.
The 15 cheapest of the 280 sources here that reach 100 dB SPL into 64Ω with at least 10 dB of headroom and no known hiss or output-impedance problem with these headphones. All 280 sources, judged for these headphones.
| Source | Type | Price | Power into 64Ω | Headroom | Verdict |
|---|---|---|---|---|---|
| JadeAudio JA11 | USB dongle | $20 | 15 mW | +12 dB | Comfortable |
| FiiO SnowSky Tiny A | USB dongle | $22 | 17 mW | +12 dB | Comfortable |
| FiiO SnowSky Tiny B | USB dongle | $22 | 17 mW | +12 dB | Comfortable |
| FiiO KA11 | USB dongle | $29 | 100 mW | +20 dB | Comfortable |
| Tanchjim Stargate II | USB dongle | $40 | 38 mW | +16 dB | Comfortable |
| ddHiFi TC35AL | USB dongle | $46 | 105 mW | +20 dB | Comfortable |
| ddHiFi TC35Air | USB dongle | $46 | 105 mW | +20 dB | Comfortable |
| Fosi Audio N3 | Bluetooth receiver | $50 | 69 mW | +18 dB | Comfortable |
| Hidizs SD2 | USB dongle | $50 | 35 mW | +16 dB | Comfortable |
| FiiO BTR13 | Bluetooth receiver | $59 | 50 mW | +17 dB | Comfortable |
| iFi GO link | USB dongle | $59 | 38 mW | +16 dB | Comfortable |
| Kiwi Ears Allegro Pro | USB dongle | $60 | 34 mW | +15 dB | Comfortable |
| ddHiFi TC35Pro (Mountain2) | USB dongle | $66 | 33 mW | +15 dB | Comfortable |
| iBasso DC03 Pro | USB dongle | $69 | 49 mW | +17 dB | Comfortable |
| DUNU DTC 480 | USB dongle | $70 | 33 mW | +15 dB | Comfortable |
Hiss. At 112.0 dB/V these are sensitive enough to reveal a source's own noise floor. The noisiest source in the database, the Schiit Mjolnir 3, would put its hiss at roughly 20 dB SPL in these headphones — clearly audible in quiet passages. Check your own source.
Output impedance. At 64Ω these want a source output impedance below 8.00Ω to satisfy the one-eighth rule; 34 of the 192 sources that publish one miss it. Check yours here.
32Ω · 110.0 dB · Easy
See requirements →28Ω · 114.0 dB · Easy
See requirements →24Ω · 109.0 dB · Easy
See requirements →32Ω · 97.0 dB · Easy
See requirements →15Ω · 94.0 dB · Easy
See requirements →15Ω · 94.0 dB · Easy
See requirements →Compared with its stablemates: vs 530 Pro · vs K5 · vs Q5 Pro.