Both are desktop DAC/amps, $459 against $349. 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 HiFiMAN EF500 reaches 100 dB on 567 of the 567 models here, the WiiM Ultra on 562.
| Specification | HiFiMAN EF500 | WiiM Ultra |
|---|---|---|
| Power into 32Ω | 1.3 W | 150 mW |
| Power into 150Ω | 282 mW | 22 mW |
| Power into 300Ω | 141 mW | 6.0 mW |
| Power into 600Ω | 70 mW | 3.0 mW |
| Output impedance | not published | not published |
| Output noise | not published | not published |
| Price | $459 | $349 |
| Headphones it reaches 100 dB on out of 567 | 567 | 562 |
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 HiFiMAN EF500 but not on the WiiM Ultra — Moondrop PARA, Sennheiser HD 600, Symphonium Crimson, 2 more.
562 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: HiFiMAN EF500 and WiiM Ultra. Or put either against your own headphones in the source comparison tool.