Both are dongles, $79 against $59. 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 iFi GO link reaches 100 dB on 556 of the 567 models here, the FiiO KA13 on 555.
| Specification | FiiO KA13 | iFi GO link |
|---|---|---|
| Power into 32Ω | 50 mW | 70 mW |
| Power into 150Ω | 10 mW | 20 mW |
| Power into 300Ω | 5.0 mW | 14 mW |
| Power into 600Ω | 2.5 mW | 7.0 mW |
| Output impedance | 1.7 Ω | 0.4 Ω |
| Output noise | 2.5 µV | not published |
| Price | $79 | $59 |
| Headphones it reaches 100 dB on out of 567 | 555 | 556 |
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.
4 headphones reach 100 dB on the FiiO KA13 but not on the iFi GO link — Moondrop PARA 2, Moondrop VENUS, Symphonium Triton, 1 more.
5 headphones reach 100 dB on the iFi GO link but not on the FiiO KA13 — Beyerdynamic DT 880 Edition (600Ω), Beyerdynamic DT 990 Edition (600Ω), HiFiMAN HE-6se V2, 2 more.
66 headphones are left alone by the iFi GO link under the one-eighth rule but coloured by the FiiO KA13 (64 Audio Aspire 1, 64 Audio Fourte, 64 Audio Nio, 63 more).
551 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 KA13 and iFi GO link. Or put either against your own headphones in the source comparison tool.