Both are dongles, $76 against $79. 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 KA13 reaches 100 dB on 555 of the 567 models here, the ddHiFi TC35Pro (Eye2) on 554.
| Specification | ddHiFi TC35Pro (Eye2) | FiiO KA13 |
|---|---|---|
| Power into 32Ω | 65 mW | 50 mW |
| Power into 150Ω | 14 mW | 10 mW |
| Power into 300Ω | 6.9 mW | 5.0 mW |
| Power into 600Ω | 3.5 mW | 2.5 mW |
| Output impedance | not published | 1.7 Ω |
| Output noise | not published | 2.5 µV |
| Price | $76 | $79 |
| Headphones it reaches 100 dB on out of 567 | 554 | 555 |
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.
3 headphones reach 100 dB on the ddHiFi TC35Pro (Eye2) but not on the FiiO KA13 — Beyerdynamic DT 880 Edition (600Ω), Beyerdynamic DT 990 Edition (600Ω), Sennheiser HD 600.
4 headphones reach 100 dB on the FiiO KA13 but not on the ddHiFi TC35Pro (Eye2) — Moondrop PARA 2, Moondrop VENUS, Symphonium Triton, 1 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: ddHiFi TC35Pro (Eye2) and FiiO KA13. Or put either against your own headphones in the source comparison tool.