The Moondrop Old Fashioned is 32Ω at 94.1 dB/mW; the Moondrop VENUS is 18Ω at 82.6 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 VENUS needs 11.5 dB more than the Old Fashioned to reach the same loudness — 55 mW against 3.9 mW.
| Specification | Old Fashioned | VENUS |
|---|---|---|
| Impedance | 32 Ω | 18 Ω |
| Sensitivity | 94.1 dB/mW | 82.6 dB/mW |
| Sensitivity (voltage) | 109.0 dB/V | 100.0 dB/V |
| Power for 100 dB | 3.9 mW | 55 mW |
| Voltage for 100 dB | 0.35 V | 0.99 V |
| Current for 100 dB | 11.0 mA | 55.3 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 4.00 Ω | 2.25 Ω |
| Sources that reach 100 dB out of 280 | 280 | 225 |
55 of the 280 sources have the power for the Old Fashioned but not for the VENUS — Apple USB-C dongle (US), Apple USB-C dongle (EU), Generic CX31993 dongles, 52 more.
225 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: Moondrop Old Fashioned and Moondrop VENUS. Every figure on this page comes from what Moondrop published, or is derived from it — what that maker publishes, counted.