Both are desktop DAC/amps, $990 against $1499. 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?
On raw power they are level: each reaches 100 dB on 567 of the 567 non-electrostatic models here.
| Specification | FiiO K17 | Matrix mini-i Pro 4 |
|---|---|---|
| Power into 32Ω | 1.9 W | 1.2 W |
| Power into 150Ω | 431 mW | 366 mW |
| Power into 300Ω | 240 mW | 260 mW |
| Power into 600Ω | 120 mW | 130 mW |
| Output impedance | 1.0 Ω | 11 Ω |
| Output noise | 5.0 µV | not published |
| Price | $990 | $1499 |
| Headphones it reaches 100 dB on out of 567 | 567 | 567 |
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.
On power they are interchangeable across this whole database: there is no headphone here that one reaches 100 dB on and the other does not.
505 headphones are left alone by the FiiO K17 under the one-eighth rule but coloured by the Matrix mini-i Pro 4 (64 Audio Aspire 1, 64 Audio Fourte, 64 Audio Ocean, 502 more).
567 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 K17 and Matrix mini-i Pro 4. Or put either against your own headphones in the source comparison tool.