The NiceHCK DB2 is 16Ω at 107.0 dB/mW; the NiceHCK F1 Pro is 16Ω at 104.0 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 F1 Pro needs 3.0 dB more than the DB2 to reach the same loudness — 0.40 mW against 0.20 mW.
| Specification | DB2 | F1 Pro |
|---|---|---|
| Impedance | 16 Ω | 16 Ω |
| Sensitivity | 107.0 dB/mW | 104.0 dB/mW |
| Sensitivity (voltage) | 125.0 dB/V | 122.0 dB/V |
| Power for 100 dB | 0.20 mW | 0.40 mW |
| Voltage for 100 dB | 57 mV | 80 mV |
| Current for 100 dB | 3.5 mA | 5.0 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 2.00 Ω | 2.00 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.
6 sources stay below the audible-hiss threshold with the F1 Pro but cross it with the DB2 (FiiO K11 R2R, Lake People G103-S Mk II, Lake People G111 Mk II, 3 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: NiceHCK DB2 and NiceHCK F1 Pro. Each figure on this page is labelled on those pages with where it came from, including the ones NiceHCK never published — what that maker publishes, counted.