The FiiO KA5 is a USB dongle at $99. It delivers 122 mW into 32Ω and 14 mW into 300Ω, which ranks it 75 of 88 for raw power among the sources in this database.
Measured at 100 dB SPL it has comfortable headroom on 278 of the 310 dynamic and planar headphones catalogued here, enough but not generous on 30 and only marginal on 2. Two DAC chips, a small display and both jacks. The step up from the KA11 for anyone who wants balanced without carrying a battery.
The manufacturer publishes 136 mW into 16Ω, 122 mW into 32Ω, 14 mW into 300Ω. Everything else in the table above is worked out from those figures, and this table says which is which.
The balanced output is rated separately: 265 mW into 32Ω through the 4.4mm jack.
Derivation holds output voltage steady between and beyond the published loads rather than output power, because that is what an amplifier actually does. The full method is written up here.
Source: fiio.com.
| Load | Power | Status | How it was arrived at |
|---|---|---|---|
| 16 Ω | 136 mW | Published | the manufacturer publishes this figure at this exact load |
| 32 Ω | 122 mW | Published | the manufacturer publishes this figure at this exact load |
| 150 Ω | 26 mW | Derived | worked out between two published loads, holding output voltage linear between them |
| 300 Ω | 14 mW | Published | the manufacturer publishes this figure at this exact load |
| 600 Ω | 6.8 mW | Derived | beyond the published loads, holding output voltage constant — which understates rather than flatters |
Ordered from easiest to hardest to drive. Headroom is measured at 100 dB SPL, which is louder than almost anyone listens — a small negative number means the source still plays loud, just without reserve for peaks.
These figures come from each manufacturer's own sensitivity rating. A handful of planars — the HiFiMAN Susvara and HE-6se and the Abyss AB-1266 in particular — are widely reported to need far more than their published sensitivity implies, so treat a bare pass on those as optimistic rather than settled.
| Headphone | Impedance | dB/mW | Needs | Headroom | Verdict |
|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 114.0 | 0.04 mW | +33 dB | Comfortable audible hiss |
| 64 Audio U12t | 13 Ω | 108.0 | 0.16 mW | +28 dB | Comfortable audible hiss |
| Shure SE215 | 17 Ω | 107.0 | 0.20 mW | +28 dB | Comfortable faint hiss |
| Moondrop Aria | 32 Ω | 107.0 | 0.20 mW | +28 dB | Comfortable faint hiss |
| Sennheiser IE 200 | 18 Ω | 104.0 | 0.40 mW | +25 dB | Comfortable faint hiss |
| Audeze LCD-X 2021 | 20 Ω | 103.0 | 0.50 mW | +24 dB | Comfortable faint hiss |
| Sennheiser HD 25 (1-II) | 70 Ω | 108.0 | 0.16 mW | +25 dB | Comfortable faint hiss |
| Sony MDR-7506 | 63 Ω | 106.0 | 0.25 mW | +24 dB | Comfortable faint hiss |
| Meze 99 Classics | 32 Ω | 103.0 | 0.50 mW | +24 dB | Comfortable faint hiss |
| Focal Clear MG | 55 Ω | 104.0 | 0.40 mW | +23 dB | Comfortable faint hiss |
| Philips SHP9500 | 32 Ω | 101.0 | 0.79 mW | +22 dB | Comfortable faint hiss |
| Truthear Hexa | 21 Ω | 99.0 | 1.3 mW | +20 dB | Comfortable |
| Focal Utopia | 80 Ω | 104.0 | 0.40 mW | +21 dB | Comfortable |
| Meze Empyrean | 32 Ω | 100.0 | 1.0 mW | +21 dB | Comfortable |
| Campfire Audio Andromeda 2020 | 9 Ω | 94.0 | 4.0 mW | +13 dB | Comfortable |
| Etymotic ER2SE | 15 Ω | 96.0 | 2.5 mW | +17 dB | Comfortable |
| AKG K371 | 32 Ω | 99.0 | 1.3 mW | +20 dB | Comfortable |
| Grado SR80x | 32 Ω | 99.0 | 1.3 mW | +20 dB | Comfortable |
| Audio-Technica ATH-M50X | 38 Ω | 99.0 | 1.3 mW | +19 dB | Comfortable |
| Beyerdynamic DT 900 Pro X | 48 Ω | 100.0 | 1.0 mW | +19 dB | Comfortable |
| Audeze LCD-2 Classic | 70 Ω | 101.0 | 0.79 mW | +18 dB | Comfortable |
| Dan Clark Audio AEON 2 Closed | 13 Ω | 92.0 | 6.3 mW | +12 dB | Comfortable |
| Sennheiser HD 560S | 120 Ω | 101.0 | 0.79 mW | +16 dB | Comfortable |
| HiFiMAN Edition XS | 18 Ω | 92.0 | 6.3 mW | +13 dB | Comfortable |
| HiFiMAN Arya Stealth | 32 Ω | 94.0 | 4.0 mW | +15 dB | Comfortable |
| Audeze LCD-5 | 14 Ω | 90.0 | 10 mW | +11 dB | Comfortable |
| HiFiMAN Sundara | 37 Ω | 94.0 | 4.0 mW | +14 dB | Comfortable |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 102.0 | 0.63 mW | +14 dB | Comfortable |
| HiFiMAN HE400se | 32 Ω | 91.0 | 7.9 mW | +12 dB | Comfortable |
| AKG K702 | 62 Ω | 93.0 | 5.0 mW | +11 dB | Comfortable |
| Fostex T50RP MK3 | 50 Ω | 92.0 | 6.3 mW | +11 dB | Comfortable |
| ZMF Verite Closed | 300 Ω | 99.0 | 1.3 mW | +10 dB | Comfortable |
| Dan Clark Audio Stealth | 23 Ω | 87.0 | 20 mW | +8 dB | Enough |
| Sennheiser HD 650 | 300 Ω | 98.0 | 1.6 mW | +9 dB | Enough |
| ZMF Atrium | 300 Ω | 98.0 | 1.6 mW | +9 dB | Enough |
| Audio-Technica ATH-R70X | 470 Ω | 99.0 | 1.3 mW | +8 dB | Enough |
| Sennheiser HD 600 | 300 Ω | 97.0 | 2.0 mW | +8 dB | Enough |
| Sennheiser HD 800S | 300 Ω | 97.0 | 2.0 mW | +8 dB | Enough |
| Beyerdynamic DT 770 Pro (250Ω) | 250 Ω | 96.0 | 2.5 mW | +8 dB | Enough |
| Abyss AB-1266 Phi TC | 42 Ω | 88.0 | 16 mW | +8 dB | Enough |
| HiFiMAN Susvara | 60 Ω | 83.0 | 50 mW | +1 dB | Marginal |
At 1.6 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 19 dB SPL, which you will hear between tracks and in quiet passages.
| In-ear | Impedance | Sensitivity | Hiss level |
|---|---|---|---|
| Shure SE846 | 9 Ω | 134.5 dB/V | 19 dB SPL |
| Moondrop Quarks | 16 Ω | 131.0 dB/V | 15 dB SPL |
| 64 Audio U4s | 12 Ω | 127.2 dB/V | 11 dB SPL |
| 64 Audio U6t | 12 Ω | 127.2 dB/V | 11 dB SPL |
| Audeze LCD-i3 | 20 Ω | 127.0 dB/V | 11 dB SPL |
At 0.3 Ω output impedance this source satisfies the one-eighth rule with every headphone in the database, down to the 8Ω in-ears. Nothing here will have its frequency response shaped by the source.
The rule is a rule of thumb, not physics: a source impedance below one eighth of the headphone's keeps the interaction under about 1 dB. The checker works it out for any pair.
$99 · 250 mW into 32Ω · not published out
Compare →$109 · 180 mW into 32Ω · 0.8 Ω out
Compare →$110 · 190 mW into 32Ω · 0.4 Ω out
Compare →$79 · 50 mW into 32Ω · 1.7 Ω out
Compare →$119 · 125 mW into 32Ω · 0.2 Ω out
Compare →$75 · 125 mW into 32Ω · 0.3 Ω out
Compare →Or put any two side by side in the source comparison tool, or run your own headphones through the amplifier matcher.