The FiiO FT1 is 32Ω at 98.0 dB/mW; the FiiO JT1 is 32Ω at 88.1 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 JT1 needs 9.9 dB more than the FT1 to reach the same loudness — 15 mW against 1.6 mW.
| Specification | FT1 | JT1 |
|---|---|---|
| Impedance | 32 Ω | 32 Ω |
| Sensitivity | 98.0 dB/mW | 88.1 dB/mW |
| Sensitivity (voltage) | 112.9 dB/V | 103.0 dB/V |
| Power for 100 dB | 1.6 mW | 15 mW |
| Voltage for 100 dB | 0.23 V | 0.70 V |
| Current for 100 dB | 7.0 mA | 22.0 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 4.00 Ω | 4.00 Ω |
| Sources that reach 100 dB out of 280 | 280 | 278 |
2 of the 280 sources have the power for the FT1 but not for the JT1 — Apple USB-C dongle (EU), Steinberg UR22C.
278 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: FiiO FT1 and FiiO JT1. Each figure on this page is labelled on those pages with where it came from, including the ones FiiO never published — what that maker publishes, counted.