The Tangzu OX Demon King is 25Ω with a sensitivity of 92.0 dB/mW, which is 108.0 dB/V. To reach 100 dB SPL — genuinely loud, louder than most people listen — it needs 6.3 mW, or 0.40 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, 229 have at least 10 dB of headroom and another 49 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.
Tangzu publishes this directly as 92 dB/mW (± 3dB @ 1000Hz), per milliwatt, so nothing was converted.
Tangzu prints the impedance as 25Ω ± 15% @ 1000Hz, not as a bare number. Everything on this page is calculated with the nominal 25Ω, 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: tangzu.net. How this data was built.
| As it is labelled | As printed | Tolerance | Standard |
|---|---|---|---|
| Frequency Response Range | 10Hz-40,000Hz | not printed | not printed |
Tangzu prints 10Hz-40,000Hz for the Tangzu OX Demon King, under the heading “Frequency Response Range”. Source: tangzu.net.
No tolerance is printed with it, so “10Hz-40,000Hz” says nothing about how loud this headphone actually is at 10 Hz.
Only what the maker printed; maker by maker.
| Level | What it is | Power | Voltage | Current |
|---|---|---|---|---|
| 85 dB SPL | quiet background listening | 0.20 mW | 71 mV | 2.8 mA |
| 95 dB SPL | normal listening | 2.0 mW | 0.22 V | 8.9 mA |
| 100 dB SPL | loud listening | 6.3 mW | 0.40 V | 15.9 mA |
| 105 dB SPL | very loud | 20 mW | 0.71 V | 28.3 mA |
| 110 dB SPL | peaks on dynamic music | 63 mW | 1.26 V | 50.2 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 25Ω 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 25Ω | Headroom | Verdict |
|---|---|---|---|---|---|
| FiiO KA11 | USB dongle | $29 | 210 mW | +15 dB | Comfortable |
| Tanchjim Stargate II | USB dongle | $40 | 75 mW | +11 dB | Comfortable |
| ddHiFi TC35AL | USB dongle | $46 | 164 mW | +14 dB | Comfortable |
| ddHiFi TC35Air | USB dongle | $46 | 164 mW | +14 dB | Comfortable |
| Fosi Audio N3 | Bluetooth receiver | $50 | 108 mW | +12 dB | Comfortable |
| FiiO BTR13 | Bluetooth receiver | $59 | 104 mW | +12 dB | Comfortable |
| iBasso DC03 Pro | USB dongle | $69 | 77 mW | +11 dB | Comfortable |
| EPZ TP35 Pro | USB dongle | $70 | 88 mW | +11 dB | Comfortable |
| Tanchjim Space | USB dongle | $70 | 98 mW | +12 dB | Comfortable |
| Truthear SHIO | USB dongle | $70 | 98 mW | +12 dB | Comfortable |
| Aiyima A2 Pro | desktop DAC/amp | $75 | 117 mW | +13 dB | Comfortable |
| Moondrop Dawn Pro | USB dongle | $75 | 98 mW | +12 dB | Comfortable |
| FiiO KA3 | USB dongle | $79 | 123 mW | +13 dB | Comfortable |
| FiiO KA5 | USB dongle | $99 | 123 mW | +13 dB | Comfortable |
| HiBy FC4 | USB dongle | $99 | 86 mW | +11 dB | Comfortable |
Hiss. At 108.0 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 16 dB SPL in these headphones — clearly audible in quiet passages. Check your own source.
Output impedance. At 25Ω these want a source output impedance below 3.12Ω to satisfy the one-eighth rule; 35 of the 192 sources that publish one miss it. Check yours here.
250Ω · 102.0 dB/mW · Easy
See requirements →250Ω · 102.0 dB/mW · Easy
See requirements →250Ω · 102.0 dB/mW · Easy
See requirements →120Ω · 98.7 dB/mW · Easy
See requirements →65Ω · 96.0 dB/mW · Easy
See requirements →50Ω · 95.2 dB/mW · Easy
See requirements →