Both are desktop DAC/amps, $176 against $199. 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 K11 R2R reaches 100 dB on 567 of the 567 models here, the Fosi Audio K7 on 566.
| Specification | FiiO K11 R2R | Fosi Audio K7 |
|---|---|---|
| Power into 32Ω | 460 mW | 600 mW |
| Power into 150Ω | 99 mW | 128 mW |
| Power into 300Ω | 50 mW | 64 mW |
| Power into 600Ω | 25 mW | 32 mW |
| Output impedance | 1.0 Ω | not published |
| Output noise | 7.2 µV | 2.5 µV |
| Price | $176 | $199 |
| 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.
| Load | FiiO K11 R2R | Fosi Audio K7 |
|---|---|---|
| 32 Ω | Published | Published |
| 150 Ω | Derived | Derived |
| 300 Ω | Published | Derived |
| 600 Ω | Derived | Derived |
Both makers publish a power rating, which is less common than the table above makes it look: of the 280 sources here, 209 publish a figure at at least one load and only 2 publish one at all four. FiiO K11 R2R publishes at 32 Ω and at 300 Ω; Fosi Audio K7 at 32 Ω. Every other row is worked out from those — between two published loads, or beyond them holding voltage constant, which understates rather than flatters.
So the two columns are not equally firm row by row: at 300 Ω only the FiiO K11 R2R figure is the maker’s own. On those rows the derived number is the one to doubt first.
What each of these labels means, and why a derived figure is still worth printing, is set out in how this data was built.
1 headphone reaches 100 dB on the FiiO K11 R2R but not on the Fosi Audio K7 — Symphonium Titan.
121 headphones stay below the audible-hiss threshold on the Fosi Audio K7 but cross it on the FiiO K11 R2R (64 Audio Aspire 1, 64 Audio Nio, 64 Audio Ocean, 118 more).
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.
The counts above say how many models the two treat differently. This says by how much. The same 8 headphones appear on every page of this kind, ordered from the easiest to drive to the hardest, so a row can be read across pages as well as across columns. Headroom is at a 100 dB SPL peak.
The widest gap on the list is the Shure SE846: FiiO K11 R2R has +40 dB of headroom there against +36 dB. 3 dB is about 2.2 times the power, which matters for peaks rather than for how loud the music sits.
Hiss is this source’s own noise, in decibels SPL, in that headphone — not a rating. Below about 20 dB SPL it is under the threshold of hearing in a quiet room; a negative figure means it is far below it.
| Headphone | Impedance | Needs | FiiO K11 R2R headroom | Fosi Audio K7 headroom | FiiO K11 R2R hiss | Fosi Audio K7 hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +40 dB | +36 dB | 32 dB | 22 dB |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +20 dB | +16 dB | 12 dB | 2 dB |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +24 dB | +25 dB | 10 dB | 1 dB |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +20 dB | +21 dB | 5 dB | -4 dB |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +18 dB | +18 dB | 4 dB | -5 dB |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +13 dB | +14 dB | -2 dB | -11 dB |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +9 dB | +10 dB | -6 dB | -15 dB |
| HiFiMAN Susvara | 60 Ω | 50 mW | +7 dB | +8 dB | -8 dB | -17 dB |
The Fosi Audio K7 costs $23 more than the FiiO K11 R2R. Out of the 567 models here, that difference buys 121 more models kept below the audible-hiss threshold.
It does not run one way only: the cheaper FiiO K11 R2R drives one model to 100 dB that the Fosi Audio K7 does not, which is the part worth checking against your own headphones before paying the difference.
Everything in this paragraph counts only figures the two makers published. An advantage on an axis one of them leaves blank cannot be counted, and is not counted — how often that happens is its own page.
Each has a page of its own with every power figure traced to what the maker published and a full headphone list: FiiO K11 R2R and Fosi Audio K7. Or put either against your own headphones in the source comparison tool.