The Shure SE215 is 17Ω at 107.0 dB/mW; the Truthear Zero:RED is 17.5Ω at 99.9 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 Truthear Zero:RED needs 7.1 dB more than the Shure SE215 to reach the same loudness — 1.0 mW against 0.20 mW.
| Specification | Shure SE215 | Truthear Zero:RED |
|---|---|---|
| Impedance | 17 Ω | 17.5 Ω |
| Sensitivity | 107.0 dB/mW | 99.9 dB/mW |
| Sensitivity (voltage) | 124.7 dB/V | 117.5 dB/V |
| Power for 100 dB | 0.20 mW | 1.0 mW |
| Voltage for 100 dB | 58 mV | 0.13 V |
| Current for 100 dB | 3.4 mA | 7.6 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 2.12 Ω | 2.19 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 stay below the audible-hiss threshold with the Truthear Zero:RED but cross it with the Shure SE215 (FiiO BTR11, FiiO K11 R2R, Lake People G103-S Mk II, 5 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 SE215 and Truthear Zero:RED. Every figure on this page comes from what Shure and Truthear published, or is derived from it — what Shure publishes and what Truthear publishes, both counted.