The Letshuoer S12 Pro is 16Ω at 102.0 dB/mW; the Moondrop Variations is 15.2Ω at 99.8 dB/mW. This page is only about what they ask of an amplifier — not how they sound, which no specification on either sheet can tell you.
The Moondrop Variations needs 2.2 dB more than the Letshuoer S12 Pro to reach the same loudness — 1.0 mW against 0.63 mW.
| Specification | Letshuoer S12 Pro | Moondrop Variations |
|---|---|---|
| Impedance | 16 Ω | 15.2 Ω |
| Sensitivity | 102.0 dB/mW | 99.8 dB/mW |
| Sensitivity (voltage) | 120.0 dB/V | 118.0 dB/V |
| Power for 100 dB | 0.63 mW | 1.0 mW |
| Voltage for 100 dB | 0.10 V | 0.13 V |
| Current for 100 dB | 6.3 mA | 8.3 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 2.00 Ω | 1.90 Ω |
| Sources that reach 100 dB out of 280 | 280 | 280 |
Every source in the database that drives one of them drives the other. On power, the choice between these two changes nothing about what amplifier you need.
3 sources are low enough in output impedance for the Letshuoer S12 Pro under the one-eighth rule but not for the Moondrop Variations (Astell&Kern HC3, RME Fireface UFX II, RME Fireface UFX III).
280 of the 280 sources here reach 100 dB on both. That count is about power only — the output-impedance and hiss lines above are separate questions, and a source can pass this one and fail those.
Each model has a page of its own with the full source list, the hiss estimate and the provenance of every figure above: Letshuoer S12 Pro and Moondrop Variations. Every figure on this page comes from what Letshuoer and Moondrop published, or is derived from it — what Letshuoer publishes and what Moondrop publishes, both counted.