The DFC uses more power than the Red or Black. AQ claim it uses less. I measured them, and it's a lie. The Black is also better than the Red and Cobalt at driving loads below about 35 Ω.What is a clear differentiator for a DFC, and an actual reason I've bought it - it has been designed with power consumption in mind. Instead of using an off the shelf USB Driver IC, the designer went for a customized solution, using a general purpose MCU in order to keep the power consumption low (remember, the newest cut of ESS chips combining USB driver+DAC+HPAmp in one IC was not available at that time).
Target achieved, even in 2021 DFC has a lowest measured power consumption among the non-single-chip dongles that can deliver around 2Vrms. And this is really important if you use it with a smaller iPhone or even an iPod Touch - the battery in those devices is not exactly huge.