The Tanchjim NORA is 16Ω at 107.0 dB/mW; the Tanchjim SODA is 15.5Ω at 101.9 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 SODA needs 5.1 dB more than the NORA to reach the same loudness — 0.65 mW against 0.20 mW.
| Specification | NORA | SODA |
|---|---|---|
| Impedance | 16 Ω | 15.5 Ω |
| Sensitivity | 107.0 dB/mW | 101.9 dB/mW |
| Sensitivity (voltage) | 125.0 dB/V | 120.0 dB/V |
| Power for 100 dB | 0.20 mW | 0.65 mW |
| Voltage for 100 dB | 57 mV | 0.10 V |
| Current for 100 dB | 3.5 mA | 6.5 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 2.00 Ω | 1.94 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 NORA under the one-eighth rule but not for the SODA (Astell&Kern HC3, RME Fireface UFX II, RME Fireface UFX III).
8 sources stay below the audible-hiss threshold with the SODA but cross it with the NORA (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: Tanchjim NORA and Tanchjim SODA. Every figure on this page comes from what Tanchjim published, or is derived from it — what that maker publishes, counted.