The FiiO FH19 is 16Ω at 109.0 dB/mW; the FiiO FX15 is 24Ω at 103.0 dB/mW. This page covers what they ask of an amplifier, not how they sound.
The FX15 needs 6.0 dB more than the FH19 to reach the same loudness — 0.50 mW against 0.13 mW.
| Specification | FH19 | FX15 |
|---|---|---|
| Impedance | 16 Ω | 24 Ω |
| Sensitivity | 109.0 dB/mW | 103.0 dB/mW |
| Sensitivity (voltage) | 127.0 dB/V | 119.2 dB/V |
| Power for 100 dB | 0.13 mW | 0.50 mW |
| Voltage for 100 dB | 45 mV | 0.11 V |
| Current for 100 dB | 2.8 mA | 4.6 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 2.00 Ω | 3.00 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.
16 sources stay below the audible-hiss threshold with the FX15 but cross it with the FH19 (FiiO BTR11, FiiO K11 R2R, Lake People G103-S Mk II, 13 more).
280 of the 280 sources here reach 100 dB on both.
The FX15 is more demanding than 36% of the 567 non-electrostatic models in this database; the FH19 than 9%.
| dB SPL | FH19 power | FH19 voltage | FX15 power | FX15 voltage |
|---|---|---|---|---|
| 80 | 1.3 µW | 4 mV | 5.0 µW | 11 mV |
| 85 | 4.0 µW | 8 mV | 0.02 mW | 20 mV |
| 90 | 0.01 mW | 14 mV | 0.05 mW | 35 mV |
| 95 | 0.04 mW | 25 mV | 0.16 mW | 62 mV |
| 100 | 0.13 mW | 45 mV | 0.50 mW | 0.11 V |
| 105 | 0.40 mW | 80 mV | 1.6 mW | 0.20 V |
| Source | Price | Headroom, FH19 | Headroom, FX15 | Output impedance | Noise |
|---|---|---|---|---|---|
| JadeAudio JA11 | $20 | 20.8 dB | 16.5 dB | 0.5 Ω | 1.7 µV |
| FiiO KA11 | $29 | 32.9 dB | 26.3 dB | 0.7 Ω | 1.7 µV |
| FiiO BTR13 | $59 | 29.8 dB | 23.2 dB | 0.6 Ω | 1.0 µV |
Of the 280 sources here, 280 reach 100 dB on both. 55 of them also publish an output impedance low enough for both under the one-eighth rule and a noise figure that stays below the audible-hiss threshold with both.
The cheapest of the 55 is the JadeAudio JA11, at $20. It leaves 20.8 dB of headroom on the FH19 and 16.5 dB on the FX15, its output impedance is 0.5 Ω against a one-eighth limit of 2.00 Ω and 3.00 Ω, and its noise figure puts the hiss floor 8 dB and 16 dB below the 20 dB SPL this site treats as the point where a quiet room stops hiding it.
| Model | As printed | Tolerance | Standard |
|---|---|---|---|
| FH19 | 8Hz-40kHz | not printed | not printed |
| FX15 | 20Hz-40kHz | not printed | not printed |
FiiO prints 8Hz-40kHz for the FH19 and 20Hz-40kHz for the FX15.
Neither range has a tolerance printed beside it, so a wider range on one sheet is not deeper bass or more treble.
Not a measurement; maker by maker.
Both have a page of their own. In full: FiiO FH19 and FiiO FX15. Every figure on this page comes from what FiiO published, or is derived from it — what that maker publishes, counted.