Both are portable amplifiers, $440 against $499. 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 Q15 reaches 100 dB on 567 of the 567 models here, the xDuoo XD05 Bal on 566.
| Specification | FiiO Q15 | xDuoo XD05 Bal |
|---|---|---|
| Power into 32Ω | 625 mW | 1.0 W |
| Power into 150Ω | 149 mW | 213 mW |
| Power into 300Ω | 85 mW | 107 mW |
| Power into 600Ω | 43 mW | 53 mW |
| Output impedance | 1.0 Ω | not published |
| Output noise | 3.1 µV | not published |
| Price | $440 | $499 |
| Headphones it reaches 100 dB on out of 567 | 567 | 566 |
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.
1 headphone reaches 100 dB on the FiiO Q15 but not on the xDuoo XD05 Bal — Symphonium Titan.
566 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 Q15 and xDuoo XD05 Bal. Or put either against your own headphones in the source comparison tool.