Both are dongles, $109 against $69. 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 DC03 Pro on 560.
| Specification | FiiO KA15 | iBasso DC03 Pro |
|---|---|---|
| Power into 32Ω | 180 mW | 98 mW |
| Power into 150Ω | 38 mW | 21 mW |
| Power into 300Ω | 19 mW | 10 mW |
| Power into 600Ω | 9.5 mW | 5.2 mW |
| Output impedance | 0.8 Ω | 0.12 Ω |
| Output noise | 1.7 µV | 0.9 µV |
| Price | $109 | $69 |
| Headphones it reaches 100 dB on out of 567 | 566 | 560 |
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.
6 headphones reach 100 dB on the FiiO KA15 but not on the iBasso DC03 Pro — Moondrop COSMO, Moondrop PARA, Moondrop PARA 2, 3 more.
12 headphones are left alone by the iBasso DC03 Pro under the one-eighth rule but coloured by the FiiO KA15 (64 Audio Nio, 64 Audio Volur, Campfire Audio Andromeda 2023, 9 more).
1 headphone stays below the audible-hiss threshold on the iBasso DC03 Pro but crosses it on the FiiO KA15 (Tanchjim EA FORCE).
560 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 DC03 Pro. Or put either against your own headphones in the source comparison tool.