The Moondrop COSMO is 15Ω at 81.8 dB/mW; the Moondrop Stellaris is 36Ω at 102.6 dB/mW. This page covers what they ask of an amplifier, not how they sound.
The COSMO needs 20.8 dB more than the Stellaris to reach the same loudness — 66 mW against 0.55 mW.
| Specification | COSMO | Stellaris |
|---|---|---|
| Impedance | 15 Ω | 36 Ω |
| Sensitivity | 81.8 dB/mW | 102.6 dB/mW |
| Sensitivity (voltage) | 100.0 dB/V | 117.0 dB/V |
| Power for 100 dB | 66 mW | 0.55 mW |
| Voltage for 100 dB | 1.00 V | 0.14 V |
| Current for 100 dB | 66.4 mA | 3.9 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 1.88 Ω | 4.50 Ω |
| Sources that reach 100 dB out of 280 | 188 | 280 |
92 of the 280 sources have the power for the Stellaris but not for the COSMO — Apple USB-C dongle (US), Apple USB-C dongle (EU), Generic CX31993 dongles, 89 more.
3 sources are low enough in output impedance for the Stellaris under the one-eighth rule but not for the COSMO (Astell&Kern HC3, RME Fireface UFX II, RME Fireface UFX III).
1 source stays below the audible-hiss threshold with the COSMO but crosses it with the Stellaris (Schiit Mjolnir 3).
188 of the 280 sources here reach 100 dB on both.
The COSMO is more demanding than 99% of the 567 non-electrostatic models in this database; the Stellaris than 44%.
| dB SPL | COSMO power | COSMO voltage | Stellaris power | Stellaris voltage |
|---|---|---|---|---|
| 80 | 0.66 mW | 100 mV | 5.5 µW | 14 mV |
| 85 | 2.1 mW | 0.18 V | 0.02 mW | 25 mV |
| 90 | 6.6 mW | 0.31 V | 0.05 mW | 44 mV |
| 95 | 21 mW | 0.56 V | 0.17 mW | 79 mV |
| 100 | 66 mW | 1.00 V | 0.55 mW | 0.14 V |
| 105 | 209 mW | 1.77 V | 1.7 mW | 0.25 V |
| Source | Price | Headroom, COSMO | Headroom, Stellaris | Output impedance | Noise |
|---|---|---|---|---|---|
| FiiO KA11 | $29 | 5.4 dB | 25.1 dB | 0.7 Ω | 1.7 µV |
| FiiO BTR13 | $59 | 2.3 dB | 22.1 dB | 0.6 Ω | 1.0 µV |
| FiiO KA3 | $79 | 2.3 dB | 23.2 dB | 0.5 Ω | 1.7 µV |
Of the 280 sources here, 188 reach 100 dB on both. 65 of them also publish an output impedance low enough for both under the one-eighth rule and a noise figure that stays below the audible-hiss threshold with both.
The cheapest of the 65 is the FiiO KA11, at $29. It leaves 5.4 dB of headroom on the COSMO and 25.1 dB on the Stellaris, its output impedance is 0.7 Ω against a one-eighth limit of 1.88 Ω and 4.50 Ω, and its noise figure puts the hiss floor 35 dB and 18 dB below the 20 dB SPL this site treats as the point where a quiet room stops hiding it.
| Model | As printed | Tolerance | Standard |
|---|---|---|---|
| COSMO | 13Hz- 58kHz (IEC61094, Free Field) | not printed | IEC61094 (free field) |
| 20Hz- 20kHz (IEC60318-4, -3dB) | -3 dB | IEC60318-4 | |
| Stellaris | 10Hz-50kHz | not printed | not printed |
| 20Hz-20kHz (IEC60318-4, 3dB) | 3 dB | IEC60318-4 |
Moondrop prints two ranges, “13Hz- 58kHz (IEC61094, Free Field)” and “20Hz- 20kHz (IEC60318-4, -3dB)”, for the COSMO and two ranges, “10Hz-50kHz” and “20Hz-20kHz (IEC60318-4, 3dB)”, for the Stellaris.
Both sheets print a tolerance, which is rare enough to be worth pointing at: only 58 of the 490 models with a printed range do. These two ranges can be set against each other, because each of them says how far down the response is allowed to be at the ends.
Not a measurement; maker by maker.
Both have a page of their own. In full: Moondrop COSMO and Moondrop Stellaris. Every figure on this page comes from what Moondrop published, or is derived from it — what that maker publishes, counted.