The Moondrop COSMO is 15Ω with a sensitivity of 81.8 dB/mW, which is 100.0 dB/V. To reach 100 dB SPL — genuinely loud, louder than most people listen — it needs 66 mW, or 1.00 V across the drivers.
That is a moderate load. Most USB dongles handle it without complaint; the weakest phone outputs will run out of volume before they run out of quality. 149 of 280 sources here have enough headroom. The cheapest portable source that does the job is the FiiO KA11 at $29.
Sensitivity here is in dB per milliwatt. Why the unit matters.
Moondrop publishes this as 100 dB/Vrms (@1kHz) — a figure per volt, not per milliwatt. At 15Ω the two differ by 18.2 dB, so the 81.8 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 18 dB easier to drive than it is — which is roughly the difference between a dongle being enough and not being enough.
Source: moondroplab.com. How this data was built.
| As it is labelled | As printed | Tolerance | Standard |
|---|---|---|---|
| Frequency range | 13Hz- 58kHz (IEC61094, Free Field) | not printed | IEC61094 (free field) |
| Effective frequency range | 20Hz- 20kHz (IEC60318-4, -3dB) | -3 dB | IEC60318-4 |
Moondrop prints two frequency ranges for the Moondrop COSMO. The wide one carries no conditions at all; the narrow one names a measurement standard and a tolerance. Only the second is a specification — the first is a headline.
This is one of only 58 models — out of the 490 whose maker prints a range at all — that also print the tolerance. That is what makes it a specification rather than a headline.
Only what the maker printed; maker by maker.
| Level | What it is | Power | Voltage | Current |
|---|---|---|---|---|
| 85 dB SPL | quiet background listening | 2.1 mW | 0.18 V | 11.8 mA |
| 95 dB SPL | normal listening | 21 mW | 0.56 V | 37.3 mA |
| 100 dB SPL | loud listening | 66 mW | 1.00 V | 66.4 mA |
| 105 dB SPL | very loud | 209 mW | 1.77 V | 118.0 mA |
| 110 dB SPL | peaks on dynamic music | 661 mW | 3.15 V | 209.9 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 15Ω 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 15Ω | Headroom | Verdict |
|---|---|---|---|---|---|
| Schiit Magni Heresy | desktop amplifier | $99 | 2.6 W | +16 dB | Comfortable |
| Schiit Magni+ | desktop amplifier | $109 | 938 mW | +12 dB | Comfortable |
| Schiit Magni Unity | desktop amplifier | $119 | 2.8 W | +16 dB | Comfortable |
| JDS Labs Atom Amp 2 | desktop amplifier | $129 | 1.2 W | +13 dB | Comfortable |
| FiiO K11 | desktop DAC/amp | $143 | 675 mW | +10 dB | Comfortable |
| Schiit Vali 3 | desktop amplifier | $149 | 703 mW | +10 dB | Comfortable |
| Topping L30 II | desktop amplifier | $149 | 3.3 W | +17 dB | Comfortable |
| SMSL HO100 | desktop amplifier | $160 | 2.8 W | +16 dB | Comfortable |
| xDuoo MT-604 | desktop amplifier | $169 | 938 mW | +12 dB | Comfortable |
| iFi Zen CAN | desktop amplifier | $199 | 750 mW | +11 dB | Comfortable |
| Geshelli Archel Pro | desktop amplifier | $200 | 844 mW | +11 dB | Comfortable |
| Schiit Magni Piety | desktop amplifier | $200 | 1.1 W | +12 dB | Comfortable |
| SMSL C200 | desktop DAC/amp | $219 | 2.4 W | +16 dB | Comfortable |
| Schiit Midgard | desktop amplifier | $219 | 5.2 W | +19 dB | Comfortable |
| Topping L50 | desktop amplifier | $229 | 3.3 W | +17 dB | Comfortable |
Hiss. At 100.0 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 8 dB SPL in these headphones — faintly audible in a silent room. Check your own source.
Output impedance. At 15Ω these want a source output impedance below 1.88Ω to satisfy the one-eighth rule; 39 of the 192 sources that publish one miss it. Check yours here.
18Ω · 82.6 dB/mW · Moderate
See requirements →9Ω · 85.5 dB/mW · Moderate
See requirements →8Ω · 80.0 dB/mW · Demanding
See requirements →300Ω · 91.8 dB/mW · Demanding
See requirements →600Ω · 96.0 dB · Moderate
See requirements →600Ω · 96.0 dB · Moderate
See requirements →Compared with its stablemates: vs HORIZON · vs JOKER · vs Old Fashioned · vs PARA · vs PARA 2 · vs SKYLAND · vs Stellaris · vs VENUS · vs Void.