The Moondrop Blessing 3 is 14.8Ω at 101.7 dB/mW; the Sennheiser IE 600 is 18Ω at 100.6 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 Sennheiser IE 600 needs 1.1 dB more than the Moondrop Blessing 3 to reach the same loudness — 0.87 mW against 0.68 mW.
| Specification | Moondrop Blessing 3 | Sennheiser IE 600 |
|---|---|---|
| Impedance | 14.8 Ω | 18 Ω |
| Sensitivity | 101.7 dB/mW | 100.6 dB/mW |
| Sensitivity (voltage) | 120.0 dB/V | 118.0 dB/V |
| Power for 100 dB | 0.68 mW | 0.87 mW |
| Voltage for 100 dB | 0.10 V | 0.13 V |
| Current for 100 dB | 6.8 mA | 7.0 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 1.85 Ω | 2.25 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.
3 sources are low enough in output impedance for the Sennheiser IE 600 under the one-eighth rule but not for the Moondrop Blessing 3 (Astell&Kern HC3, RME Fireface UFX II, RME Fireface UFX III).
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 Blessing 3 and Sennheiser IE 600. Every figure on this page comes from what Moondrop and Sennheiser published, or is derived from it — what Moondrop publishes and what Sennheiser publishes, both counted.