The Moondrop Aria 2 is 33Ω at 107.2 dB/mW; the Moondrop Armature Art 12 is 5Ω at 98.0 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 Armature Art 12 needs 9.2 dB more than the Aria 2 to reach the same loudness — 1.6 mW against 0.19 mW.
| Specification | Aria 2 | Armature Art 12 |
|---|---|---|
| Impedance | 33 Ω | 5 Ω |
| Sensitivity | 107.2 dB/mW | 98.0 dB/mW |
| Sensitivity (voltage) | 122.0 dB/V | 121.0 dB/V |
| Power for 100 dB | 0.19 mW | 1.6 mW |
| Voltage for 100 dB | 79 mV | 89 mV |
| Current for 100 dB | 2.4 mA | 17.8 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 4.12 Ω | 0.62 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.
54 sources are low enough in output impedance for the Aria 2 under the one-eighth rule but not for the Armature Art 12 (FiiO SnowSky Tiny B, FiiO KA11, FiiO KA13, 51 more).
2 sources stay below the audible-hiss threshold with the Armature Art 12 but cross it with the Aria 2 (FiiO BTR11, Rupert Neve RNHP).
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: Moondrop Aria 2 and Moondrop Armature Art 12. Every figure on this page comes from what Moondrop published, or is derived from it — what that maker publishes, counted.