Both are dongles, $109 against $119. This page puts them side by side on the only three things a maker can be held to — power, output impedance and noise — and then asks the question that actually matters: which headphones do they treat differently?
The FiiO KA15 reaches 100 dB on 566 of the 567 models here, the iBasso DC04 Pro on 561.
| Specification | FiiO KA15 | iBasso DC04 Pro |
|---|---|---|
| Power into 32Ω | 180 mW | 125 mW |
| Power into 150Ω | 38 mW | 27 mW |
| Power into 300Ω | 19 mW | 13 mW |
| Power into 600Ω | 9.5 mW | 6.7 mW |
| Output impedance | 0.8 Ω | 0.2 Ω |
| Output noise | 1.7 µV | 2.5 µV unverified |
| Price | $109 | $119 |
| Headphones it reaches 100 dB on out of 567 | 566 | 561 |
A figure marked not published is missing from the maker’s own material, which is not the same as being good or bad. Where one of these two publishes a number and the other does not, the comparison on that axis cannot be made at all — and saying so is more useful than guessing.
5 headphones reach 100 dB on the FiiO KA15 but not on the iBasso DC04 Pro — Moondrop COSMO, Moondrop PARA, Symphonium Crimson, 2 more.
12 headphones are left alone by the iBasso DC04 Pro under the one-eighth rule but coloured by the FiiO KA15 (64 Audio Nio, 64 Audio Volur, Campfire Audio Andromeda 2023, 9 more).
561 of the 567 models here reach 100 dB on both. That is a power count and nothing more; whether either source suits a given headphone also depends on the two lines above.
Each has a page of its own with every power figure traced to what the maker published and a full headphone list: FiiO KA15 and iBasso DC04 Pro. Or put either against your own headphones in the source comparison tool.