because the asus sound card is better . you say why its is better ? my answer : bigger is better every one knows that but if you got a small one then you will say it doesn't matter but that would be lying to yourself and to make yourself feel better ..
actually the asus has more stuff than the fiio it has dolby suit with headphone proligic and other things , vocal fx , mic and headphone amp up to 600 ohm , most importantly fine gold caps which is made for audio products .. many dac's use black unnamed caps or named mother board caps dont say its mother board caps but its 2 k or 5 k or 10k basically no mobo caps are good for sound