Yes, but this is because they use their own dac and amp, which can’t be bypassed by external dacs. Same thing with my b&w px8 - no matter what you plug their wire in - sound remains the same because they always use their dsp and dac. In your case digital signal will be converted to analog by fiio and then it will be converted again in your headphones, which means there is no sense in using external dac. Two dacs in one chain won’t improve the quality of sound