Nothing is perfect: the more revealing your system is, the more you can hear external influences. For argument’s sake even with a perfect DAC, it could simply be the source or digital interconnects, WiFi, etc. radiating or generating conducted noise affecting some other link, groundloop or component. If you have another non-digital source and select it but leave the digital input path running do you still hear the effects?
Multiple of my guests have heard the difference with my laptop’s WiFi turned on and off while playing my system (I’ve run blind experiments watching their faces as they listen and I turn off and on the WiFi with a small external switch on my old laptops.) I just can’t be bothered worrying about it, I like to use access the net, etc. and have my cell phone available while playing music from my laptop…