Short answer
Both are portable amplifiers, $750 against $499.
The FiiO Q7 reaches 100 dB on 567 of the 567 models here, the xDuoo XD05 Bal on 566.
| Specification | FiiO Q7 | xDuoo XD05 Bal |
|---|---|---|
| Power into 32Ω | 550 mW | 1.0 W |
| Power into 150Ω | 123 mW | 213 mW |
| Power into 300Ω | 65 mW | 107 mW |
| Power into 600Ω | 33 mW | 53 mW |
| Output impedance | 1.2 Ω | not published |
| Output noise | 2.8 µV | not published |
| Price | $750 | $499 |
| Headphones it reaches 100 dB on out of 567 | 567 | 566 |
Not published means the maker leaves it out, so that axis cannot be compared.
| Balanced | FiiO Q7 | xDuoo XD05 Bal |
|---|---|---|
| Socket | 4.4mm | 4.4mm |
| Power into 32Ω | 1.5 W | 1.0 W |
| Power into 300Ω | 260 mW | 107 mW derived |
| Output impedance | 2.2 Ω | not published |
| Output noise | 4.5 µV | not published |
| Headphones it reaches 100 dB on out of 567 | 567 | 566 |
Through the balanced sockets the FiiO Q7 reaches 100 dB on 567 of the 567 models here and the xDuoo XD05 Bal on 566. Derived figures are worked out from the loads the maker did publish.
| Load | FiiO Q7 | xDuoo XD05 Bal |
|---|---|---|
| 32 Ω | Published | Published |
| 150 Ω | Derived | Derived |
| 300 Ω | Published | Derived |
| 600 Ω | Derived | Derived |
Both makers publish a power rating. FiiO Q7 publishes at 32 Ω and at 300 Ω; xDuoo XD05 Bal at 32 Ω. The other rows are worked out from those.
So the two columns are not equally firm row by row: at 300 Ω only the FiiO Q7 figure is the maker’s own. On those rows the derived number is the one to doubt first.
1 headphone reaches 100 dB on the FiiO Q7 but not on the xDuoo XD05 Bal — Symphonium Titan.
566 of the 567 models here reach 100 dB on both.
Headroom is at a 100 dB SPL peak.
The widest gap on the list is the HiFiMAN Susvara: xDuoo XD05 Bal has +10 dB of headroom there against +8 dB. 3 dB is about 1.8 times the power, which matters for peaks rather than for how loud the music sits.
The hiss columns are empty for xDuoo XD05 Bal because that maker publishes no output noise figure.
| Headphone | Impedance | Needs | FiiO Q7 headroom | xDuoo XD05 Bal headroom | FiiO Q7 hiss | xDuoo XD05 Bal hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +40 dB damping | +38 dB | 23 dB | not published |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +20 dB damping | +18 dB | 3 dB | not published |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +25 dB | +28 dB | 1 dB | not published |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +21 dB | +23 dB | -3 dB | not published |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +19 dB | +20 dB | -4 dB | not published |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +14 dB | +16 dB | -10 dB | not published |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +10 dB | +12 dB | -14 dB | not published |
| HiFiMAN Susvara | 60 Ω | 50 mW | +8 dB | +10 dB | -16 dB | not published |
The FiiO Q7 costs $251 more than the xDuoo XD05 Bal. Out of the 567 models here, that difference buys 1 more model driven to 100 dB.
Nothing runs the other way: there is no axis here on which the cheaper of the two does better.
Only published figures count here; blank axes are counted separately.
Each in full: FiiO Q7 and xDuoo XD05 Bal.