FiiO K19: power output and what it will drive

The FiiO K19 is a desktop DAC/amp at $1430. It delivers 2.3 W into 32Ω and 270 mW into 300Ω, which ranks it 38 of 280 for raw power among the sources in this database.

Measured at 100 dB SPL it has comfortable headroom on 570 of the 571 dynamic and planar headphones catalogued here and enough but not generous on 1. Power is published at 16Ω, 32Ω, 300Ω; the rest of the table is derived from those figures.

The manufacturer publishes 4.0 W into 16Ω, 2.3 W into 32Ω, 270 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: 8.0 W into 32Ω through the 4.4mm / XLR4 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, fiio.com.

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.

At 3.5 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.

At 0.6 Ω output impedance, the one-eighth rule says this source suits headphones of 4.8Ω and above. 1 of the 571 models here falls below that. The one model below that line is the Symphonium Titan, and the mismatch tilts the frequency response audibly rather than subtly.

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.

Or put any two side by side in the source comparison tool, or run your own headphones through the amplifier matcher. Or see every FiiO source in the database, and how much of what this site says about them came from FiiO’s own documents.