Both are portable amplifiers, $440 against $750. 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 Q15 | FiiO Q7 |
|---|---|---|
| Power into 32Ω | 625 mW | 550 mW |
| Power into 150Ω | 149 mW | 123 mW |
| Power into 300Ω | 85 mW | 65 mW |
| Power into 600Ω | 43 mW | 33 mW |
| Output impedance | 1.0 Ω | 1.2 Ω |
| Output noise | 3.1 µV | 2.8 µV |
| Price | $440 | $750 |
| 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.
23 headphones are left alone by the FiiO Q15 under the one-eighth rule but coloured by the FiiO Q7 (64 Audio Ocean, 64 Audio U18s, 64 Audio U6t, 20 more).
4 headphones stay below the audible-hiss threshold on the FiiO Q7 but cross it on the FiiO Q15 (AFUL Performer 8, Campfire Audio Chimera, Dunu SA6 MKII, 1 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 Q15 and FiiO Q7. Or put either against your own headphones in the source comparison tool.