The Tanchjim EA FORCE is 17Ω at 120.0 dB (no reference unit printed); the Tanchjim OLA II is 30Ω at 105.8 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 OLA II needs 14.2 dB more than the EA FORCE to reach the same loudness — 0.26 mW against 0.01 mW.
| Specification | EA FORCE | OLA II |
|---|---|---|
| Impedance | 17 Ω | 30 Ω |
| Sensitivity | 120.0 dB | 105.8 dB/mW |
| Sensitivity (voltage) | 137.7 dB/V | 121.0 dB/V |
| Power for 100 dB | 0.01 mW | 0.26 mW |
| Voltage for 100 dB | 13 mV | 89 mV |
| Current for 100 dB | 0.8 mA | 3.0 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 2.12 Ω | 3.75 Ω |
| Sources that reach 100 dB out of 280 | 280 | 280 |
One caution before reading the rows. Tanchjim EA FORCE 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.
57 sources stay below the audible-hiss threshold with the OLA II but cross it with the EA FORCE (JadeAudio JA11, Kiwi Ears Allegro Mini, FiiO KA11, 54 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 EA FORCE and Tanchjim OLA II. Each figure on this page is labelled on those pages with where it came from, including the ones Tanchjim never published — what that maker publishes, counted.