The Shure SE846 is 9Ω at 114.0 dB/mW; the Thieaudio Monarch MK3 is 20Ω at 99.0 dB (no reference unit printed). 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 Thieaudio Monarch MK3 needs 15.0 dB more than the Shure SE846 to reach the same loudness — 1.3 mW against 0.04 mW.
| Specification | Shure SE846 | Thieaudio Monarch MK3 |
|---|---|---|
| Impedance | 9 Ω | 20 Ω |
| Sensitivity | 114.0 dB/mW | 99.0 dB |
| Sensitivity (voltage) | 134.5 dB/V | 116.0 dB/V |
| Power for 100 dB | 0.04 mW | 1.3 mW |
| Voltage for 100 dB | 19 mV | 0.16 V |
| Current for 100 dB | 2.1 mA | 7.9 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 1.12 Ω | 2.50 Ω |
| Sources that reach 100 dB out of 280 | 280 | 280 |
One caution before reading the rows. Thieaudio Monarch MK3 printed a decibel figure with no reference unit, so this page reads it as per milliwatt. If it is really per volt, that model needs far more than the table says. Why the two readings differ by so much.
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.
11 sources are low enough in output impedance for the Thieaudio Monarch MK3 under the one-eighth rule but not for the Shure SE846 (FiiO KA13, FiiO K11, Schiit Vali 2+, 8 more).
41 sources stay below the audible-hiss threshold with the Thieaudio Monarch MK3 but cross it with the Shure SE846 (Kiwi Ears Allegro Mini, FiiO BTR11, FiiO KA13, 38 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: Shure SE846 and Thieaudio Monarch MK3. Each figure on this page is labelled on those pages with where it came from, including the ones Shure and Thieaudio never published — what Shure publishes and what Thieaudio publishes, both counted.