The Moondrop Aria 2 is 33Ω at 107.2 dB/mW; the Moondrop Armature Art 24 is 5.8Ω at 96.6 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 Armature Art 24 needs 10.6 dB more than the Aria 2 to reach the same loudness — 2.2 mW against 0.19 mW.
| Specification | Aria 2 | Armature Art 24 |
|---|---|---|
| Impedance | 33 Ω | 5.8 Ω |
| Sensitivity | 107.2 dB/mW | 96.6 dB/mW |
| Sensitivity (voltage) | 122.0 dB/V | 119.0 dB/V |
| Power for 100 dB | 0.19 mW | 2.2 mW |
| Voltage for 100 dB | 79 mV | 0.11 V |
| Current for 100 dB | 2.4 mA | 19.4 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 4.12 Ω | 0.72 Ω |
| Sources that reach 100 dB out of 280 | 280 | 279 |
1 of the 280 sources has the power for the Aria 2 but not for the Armature Art 24 — Steinberg UR22C.
49 sources are low enough in output impedance for the Aria 2 under the one-eighth rule but not for the Armature Art 24 (FiiO SnowSky Tiny B, FiiO KA13, FiiO KA15, 46 more).
2 sources stay below the audible-hiss threshold with the Armature Art 24 but cross it with the Aria 2 (FiiO BTR11, Rupert Neve RNHP).
279 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.
The gap between these two in decibels does not change with volume — it is a property of the two headphones. What changes is the size of the numbers, and it changes fast: every 10 dB costs ten times the power. The row that matters is the one nearest the level you listen at, and for most people that is nearer the top of this table than the bottom.
The Armature Art 24 is more demanding than 37% of the 567 non-electrostatic models in this database; the Aria 2 than 25%. Both figures use the same measure as the rest of the site: whichever runs out first against a 2 V, 100 mW dongle, voltage or power.
| dB SPL | Aria 2 power | Aria 2 voltage | Armature Art 24 power | Armature Art 24 voltage |
|---|---|---|---|---|
| 80 | 1.9 µW | 8 mV | 0.02 mW | 11 mV |
| 85 | 6.0 µW | 14 mV | 0.07 mW | 20 mV |
| 90 | 0.02 mW | 25 mV | 0.22 mW | 36 mV |
| 95 | 0.06 mW | 45 mV | 0.69 mW | 63 mV |
| 100 | 0.19 mW | 79 mV | 2.2 mW | 0.11 V |
| 105 | 0.60 mW | 0.14 V | 6.9 mW | 0.20 V |
105 dB is included because forum power figures are usually quoted there or higher. It is also a level that damages hearing in minutes — how many minutes is its own calculator.
| Source | Price | Headroom, Aria 2 | Headroom, Armature Art 24 | Output impedance | Noise |
|---|---|---|---|---|---|
| JadeAudio JA11 | $20 | 21.8 dB | 4.0 dB | 0.5 Ω | 1.7 µV |
| FiiO KA11 | $29 | 30.1 dB | 16.1 dB | 0.7 Ω | 1.7 µV |
| FiiO BTR13 | $59 | 27.1 dB | 13.0 dB | 0.6 Ω | 1.0 µV |
Of the 280 sources here, 279 reach 100 dB on both. That is the easy axis. 41 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 rest either fail one of those or never printed the number at all, and 207 of them are in the second group.
The cheapest of the 41 is the JadeAudio JA11, at $20. It leaves 21.8 dB of headroom on the Aria 2 and 4.0 dB on the Armature Art 24, its output impedance is 0.5 Ω against a one-eighth limit of 4.12 Ω and 0.72 Ω, and its noise figure puts the hiss floor 13 dB and 16 dB below the 20 dB SPL this site treats as the point where a quiet room stops hiding it.
Cheapest that satisfies three published numbers is not the same as best, and none of it is about how either headphone sounds. To put either model against a source this page does not mention, or to change the target loudness, use the amplifier matcher.
| Model | As printed | Tolerance | Standard |
|---|---|---|---|
| Aria 2 | 16Hz - 22kHz (IEC61094, Free Field) | not printed | IEC61094 (free field) |
| 20Hz - 20kHz (IEC60318-4, -3dB) | -3 dB | IEC60318-4 | |
| Armature Art 24 | 7Hz-35kHz | not printed | not printed |
| 20Hz-20kHz (IEC60318-4, -3dB) | -3 dB | IEC60318-4 |
Moondrop prints two ranges, “16Hz - 22kHz (IEC61094, Free Field)” and “20Hz - 20kHz (IEC60318-4, -3dB)”, for the Aria 2 and two ranges, “7Hz-35kHz” and “20Hz-20kHz (IEC60318-4, -3dB)”, for the Armature Art 24.
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.
None of this is a measurement. What each maker publishes, and what it is worth, is set out in the frequency response audit.
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 24. Every figure on this page comes from what Moondrop published, or is derived from it — what that maker publishes, counted.