The Oriolus Isabellae is 30Ω at 113.0 dB/mW; the Oriolus Szalayi is 10Ω at 110.0 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 Szalayi needs 3.0 dB more than the Isabellae to reach the same loudness — 0.10 mW against 0.05 mW.
| Specification | Isabellae | Szalayi |
|---|---|---|
| Impedance | 30 Ω | 10 Ω |
| Sensitivity | 113.0 dB/mW | 110.0 dB/mW |
| Sensitivity (voltage) | 128.2 dB/V | 130.0 dB/V |
| Power for 100 dB | 0.05 mW | 0.10 mW |
| Voltage for 100 dB | 39 mV | 32 mV |
| Current for 100 dB | 1.3 mA | 3.2 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 3.75 Ω | 1.25 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.
8 sources are low enough in output impedance for the Isabellae under the one-eighth rule but not for the Szalayi (FiiO KA13, Schiit Vali 2+, Astell&Kern HC3, 5 more).
4 sources stay below the audible-hiss threshold with the Isabellae but cross it with the Szalayi (FiiO M15S, FiiO K19, FiiO M17, 1 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: Oriolus Isabellae and Oriolus Szalayi. Every figure on this page comes from what Oriolus published, or is derived from it — what that maker publishes, counted.