The Meze 109 Pro is 40Ω at 112.0 dB/mW; the Meze STRADA is 40Ω at 111.0 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 STRADA needs 1.0 dB more than the 109 Pro to reach the same loudness — 0.08 mW against 0.06 mW.
| Specification | 109 Pro | STRADA |
|---|---|---|
| Impedance | 40 Ω | 40 Ω |
| Sensitivity | 112.0 dB/mW | 111.0 dB/mW |
| Sensitivity (voltage) | 126.0 dB/V | 125.0 dB/V |
| Power for 100 dB | 0.06 mW | 0.08 mW |
| Voltage for 100 dB | 50 mV | 56 mV |
| Current for 100 dB | 1.3 mA | 1.4 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 5.00 Ω | 5.00 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.
5 sources stay below the audible-hiss threshold with the STRADA but cross it with the 109 Pro (FiiO M33 R2R, SPL Phonitor se, SPL Phonitor xe, 2 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 STRADA. Every figure on this page comes from what Meze published, or is derived from it — what that maker publishes, counted.