The Meze 109 Pro is 40Ω at 112.0 dB/mW; the Meze ARTA is 225Ω 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 ARTA needs 14.0 dB more than the 109 Pro to reach the same loudness — 1.6 mW against 0.06 mW.
| Specification | 109 Pro | ARTA |
|---|---|---|
| Impedance | 40 Ω | 225 Ω |
| Sensitivity | 112.0 dB/mW | 98.0 dB/mW |
| Sensitivity (voltage) | 126.0 dB/V | 104.5 dB/V |
| Power for 100 dB | 0.06 mW | 1.6 mW |
| Voltage for 100 dB | 50 mV | 0.60 V |
| Current for 100 dB | 1.3 mA | 2.7 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 5.00 Ω | 28.12 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.
18 sources are low enough in output impedance for the ARTA under the one-eighth rule but not for the 109 Pro (Zoom AMS-22, Arturia MiniFuse 2, Arturia MiniFuse 1, 15 more).
13 sources stay below the audible-hiss threshold with the ARTA but cross it with the 109 Pro (FiiO BTR11, FiiO K11 R2R, Lake People G103-S Mk II, 10 more).
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: Meze 109 Pro and Meze ARTA. Every figure on this page comes from what Meze published, or is derived from it — what that maker publishes, counted.