Another DAC? you might say to yourselves. In fact, this is the companion to the Sony SRS-X11 because the FiiO K1 is about the same size as a flash drive just as the X11 is a fairly small and therefore portable speaker in the way my Logitech X300s aren’t quite. Portability is the key to this.
The sound seems fairly decent for such a small DAC, but not as good, I think, as the E17K (which, in turn, is possibly not quite as good as the PHA-1A). It’s powered by the laptop, but doesn’t appear to be demanding, although I’d have to try it on battery power only to see whether it had any significant effect.
The K1 can be connected to a laptop (I normally have it attached to my 5755), and will work without any problems when it’s connected to my iPod Touch via a lightning-to-USB cable (or even better, the lightning-to-USB 3 camera adaptor as recommended by Audioquest for the Dragonfly).
It has 16-bit modes from 32KHz to 96KHz and 24-bit modes from 44.1KHz to 96KHz (according to Control Panel), and uses the same DAC chip as the E17K.
I’d say that the K1 and the Dragonfly are best connected to devices like the iPod Touch or something similar which has a digital connection, but which can handle the power requirements.
In comparison with the Dragonfly Red, the K1 doesn’t quite have the richness, but the difference is a wafer or two even though the K1 is only about a quarter of the price of the Dragonfly. The K1 puts in a decent performance.
If your headphones don’t have their own external volume control (or a proprietary one such as my Momentums, which have a controller that only works with iPods), then the system volume needs to be turned right down. I find <= 5% about right.
My overall conclusion is that USB DACs have their uses, but with the right sort of device. They can be used with laptops, but they are probably better paired with devices such as iPods or tablets.