Both are dongles, $9 against $9. 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 Apple USB-C dongle (US) reaches 100 dB on 547 of the 567 models here, the Apple USB-C dongle (EU) on 516.
| Specification | Apple USB-C dongle (EU) | Apple USB-C dongle (US) |
|---|---|---|
| Power into 32Ω | 15 mW | 30 mW |
| Power into 150Ω | 4.0 mW | 8.0 mW |
| Power into 300Ω | 2.0 mW | 4.0 mW |
| Power into 600Ω | 1.0 mW | 2.0 mW |
| Output impedance | 1 Ω unverified | 1 Ω unverified |
| Output noise | 6 µV unverified | 6 µV unverified |
| Price | $9 | $9 |
| Headphones it reaches 100 dB on out of 567 | 516 | 547 |
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.
31 headphones reach 100 dB on the Apple USB-C dongle (US) but not on the Apple USB-C dongle (EU) — AKG K612 Pro, Abyss AB-1266 Phi CC, Abyss AB-1266 Phi TC, 28 more.
516 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 a full headphone list and the provenance of every figure — worth opening here, because Apple USB-C dongle (EU) and Apple USB-C dongle (US) have published no electrical specification at all and everything above comes from independent measurement: Apple USB-C dongle (EU) and Apple USB-C dongle (US). Or put either against your own headphones in the source comparison tool.