The Fosi Audio K7 is a desktop DAC/amp at $199. It delivers 600 mW into 32Ω and 64 mW into 300Ω, which ranks it 98 of 280 for raw power among the sources in this database.
Measured at 100 dB SPL it has comfortable headroom on 552 of the 567 dynamic and planar headphones catalogued here, enough but not generous on 13, only marginal on 1 and not enough power for 1. Power is published at 32Ω; the rest of the table is derived from those figures. Output impedance is not published.
The manufacturer publishes 600 mW into 32Ω. The rest of the table is worked out from those.
The balanced output is rated separately: 2.1 W into 32Ω through the 4.4mm jack.
Derived rows hold output voltage steady, as an amplifier does (method).
Source: fosiaudio.com, fosiaudio.com.
| Load | Power | Status | How it was arrived at |
|---|---|---|---|
| 32 Ω | 600 mW | Published | the manufacturer publishes this figure at this exact load |
| 150 Ω | 128 mW | Derived | beyond the published loads, holding output voltage constant — which understates rather than flatters |
| 300 Ω | 64 mW | Derived | beyond the published loads, holding output voltage constant — which understates rather than flatters |
| 600 Ω | 32 mW | Derived | beyond the published loads, holding output voltage constant — which understates rather than flatters |
Easiest to hardest to drive, with headroom at a 100 dB SPL peak.
| Headphone | Impedance | Sensitivity | Needs | Headroom | Verdict |
|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 114.0 dB/mW | 0.04 mW | +36 dB | Comfortable audible hiss |
| 64 Audio U12t | 12.6 Ω | 108.0 dB/mW | 0.16 mW | +32 dB | Comfortable audible hiss |
| Shure SE215 | 17 Ω | 107.0 dB/mW | 0.20 mW | +32 dB | Comfortable audible hiss |
| Moondrop Aria | 32 Ω | 107.1 dB/mW | 0.19 mW | +35 dB | Comfortable audible hiss |
| Audeze LCD-X 2021 | 20 Ω | 103.0 dB/mW | 0.50 mW | +29 dB | Comfortable faint hiss |
| Truthear Hexa | 20.5 Ω | 103.1 dB/mW | 0.49 mW | +29 dB | Comfortable faint hiss |
| Sennheiser IE 200 | 18 Ω | 101.6 dB/mW | 0.69 mW | +27 dB | Comfortable faint hiss |
| Sony MDR-7506 | 63 Ω | 106.0 dB/mW | 0.25 mW | +31 dB | Comfortable faint hiss |
| Meze 99 Classics | 32 Ω | 103.0 dB/mW | 0.50 mW | +31 dB | Comfortable faint hiss |
| Focal Clear MG | 55 Ω | 104.0 dB/mW | 0.40 mW | +29 dB | Comfortable faint hiss |
| Philips SHP9500 | 32 Ω | 101.0 dB | 0.79 mW | +29 dB | Comfortable faint hiss |
| Focal Utopia | 80 Ω | 104.0 dB/mW | 0.40 mW | +28 dB | Comfortable faint hiss |
| Meze Empyrean | 32 Ω | 100.0 dB | 1.0 mW | +28 dB | Comfortable faint hiss |
| Campfire Audio Andromeda 2020 | 9 Ω | 94.0 dB | 4.0 mW | +16 dB | Comfortable faint hiss |
| Etymotic ER2SE | 15 Ω | 96.0 dB/mW | 2.5 mW | +20 dB | Comfortable faint hiss |
| AKG K371 | 32 Ω | 99.1 dB/mW | 1.2 mW | +27 dB | Comfortable faint hiss |
| Audio-Technica ATH-M50X | 38 Ω | 99.0 dB/mW | 1.3 mW | +26 dB | Comfortable faint hiss |
| Beyerdynamic DT 900 Pro X | 48 Ω | 100.0 dB/mW | 1.0 mW | +26 dB | Comfortable faint hiss |
| Audeze LCD-2 Classic | 70 Ω | 101.0 dB/mW | 0.79 mW | +25 dB | Comfortable faint hiss |
| Grado SR80x | 38 Ω | 98.0 dB/mW | 1.6 mW | +25 dB | Comfortable faint hiss |
| Sennheiser HD 560S | 120 Ω | 100.8 dB/mW | 0.83 mW | +23 dB | Comfortable |
| HiFiMAN Edition XS | 18 Ω | 92.0 dB | 6.3 mW | +17 dB | Comfortable |
| HiFiMAN Arya Stealth | 32 Ω | 94.0 dB | 4.0 mW | +22 dB | Comfortable |
| Dan Clark Audio AEON 2 Closed | 13 Ω | 90.0 dB/mW | 10 mW | +14 dB | Comfortable |
| Audeze LCD-5 | 14 Ω | 90.0 dB/mW | 10 mW | +14 dB | Comfortable |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 102.0 dB/mW | 0.63 mW | +21 dB | Comfortable |
| HiFiMAN HE400se | 25 Ω | 91.0 dB | 7.9 mW | +18 dB | Comfortable |
| HiFiMAN Sundara | 32 Ω | 92.0 dB | 6.3 mW | +20 dB | Comfortable |
| Dan Clark Audio Stealth | 23 Ω | 90.0 dB/mW | 10 mW | +16 dB | Comfortable |
| Fostex T50RP MK3 | 50 Ω | 92.0 dB/mW | 6.3 mW | +18 dB | Comfortable |
| AKG K702 | 62 Ω | 92.9 dB/mW | 5.1 mW | +18 dB | Comfortable |
| ZMF Verite Closed | 300 Ω | 99.0 dB/mW | 1.3 mW | +17 dB | Comfortable |
| Sennheiser HD 650 | 300 Ω | 97.8 dB/mW | 1.7 mW | +16 dB | Comfortable |
| Sennheiser HD 800S | 300 Ω | 96.8 dB/mW | 2.1 mW | +15 dB | Comfortable |
| Beyerdynamic DT 770 Pro (250Ω) | 250 Ω | 96.0 dB | 2.5 mW | +15 dB | Comfortable |
| Audio-Technica ATH-R70X | 470 Ω | 98.0 dB/mW | 1.6 mW | +14 dB | Comfortable |
| ZMF Atrium | 300 Ω | 96.0 dB/mW | 2.5 mW | +14 dB | Comfortable |
| Abyss AB-1266 Phi TC | 50 Ω | 88.0 dB/mW | 16 mW | +14 dB | Comfortable |
| Sennheiser HD 600 | 300 Ω | 91.8 dB/mW | 6.6 mW | +10 dB | Enough |
| HiFiMAN Susvara | 60 Ω | 83.0 dB | 50 mW | +8 dB | Enough |
At 2.5 µV of output noise, here is where that noise lands in the five most revealing in-ears in the database.
This one hisses. With the most sensitive in-ears in the database its own noise lands around 29 dB SPL, which you will hear between tracks and in quiet passages.
| In-ear | Impedance | Sensitivity | Hiss level |
|---|---|---|---|
| Simgot EA500 | 16 Ω | 141.0 dB/V | 29 dB SPL |
| Tanchjim EA FORCE | 17 Ω | 137.7 dB/V | 26 dB SPL |
| Shure SE846 | 9 Ω | 134.5 dB/V | 22 dB SPL |
| Campfire Audio Clara | 13.3 Ω | 134.1 dB/V | 22 dB SPL |
| 64 Audio Fourte | 10 Ω | 134.0 dB/V | 22 dB SPL |
The manufacturer does not publish an output impedance for this source. Without it, nothing here can say how this source will behave with a multi-driver in-ear.
With a measured figure, the checker works out the consequence.
| As published | Fosi Audio K7 |
|---|---|
| DAC | AK4493SEQ |
| Outputs | 4.4 mm balanced, 3.5 mm SE, RCA |
| Inputs | USB-C, optical, coaxial, Bluetooth, 3.5 mm microphone |
| Bluetooth | Bluetooth 5.0; SBC, AAC, aptX, aptX HD, aptX LL |
| Formats | USB: PCM 384 kHz/32-bit, DSD256 |
| Power supply | External DC 12 V / 2 A adapter |
Copied from the makers’ own pages: fosiaudio.com/pages/fosi-audio-k7-dac-amp. Battery life is the maker’s own test figure.
| Source | Type | Price | Into 300 Ω | Output impedance | Output noise |
|---|---|---|---|---|---|
| FiiO KA11 | USB dongle | $29 | 22 mW | 0.7 Ω | 1.7 µV |
| JDS Labs Atom+ (2nd gen) | desktop amplifier | $99 | 272 mW | 0.7 Ω | 1.99 µV |
| FiiO KA15 | USB dongle | $109 | 19 mW | 0.8 Ω | 1.7 µV |
Of the 280 sources here, 7 do everything the Fosi Audio K7 does as a headphone output: reach 100 dB on every headphone it reaches and stay under the audible-hiss threshold wherever it does. The cheapest of them is the FiiO KA11 at $29, against this one’s $199 — $170 less, and a USB dongle rather than a desktop DAC/amp.
The cheaper one also publishes an output impedance, which the Fosi Audio K7 does not — so on the paperwork it is ahead, not merely level.
This counts the headphone output only; inputs, converters, the volume control and the build are outside it.
$199 · 1.2 W into 32Ω · 1.0 Ω out
Compare →$219 · 1.3 W into 32Ω · output Ω not published
Compare →$176 · 460 mW into 32Ω · 1.0 Ω out
Compare →$170 · 100 mW into 32Ω · output Ω not published
Compare →$229 · 210 mW into 32Ω · 1 Ω out
Compare →$143 · 520 mW into 32Ω · 1.2 Ω out
Compare →Compared with its closest rivals: vs FiiO K11 R2R · vs FiiO K7 · vs SMSL C200.