From a PC's motherboard, whether Optical S/PDIF or USB, which output will allow for a better sound when connecting a DAC/headphone amplifier? Does USB 2.0 or 3.0 matter? Do the types of cables used matter (higher quality)? Does cable length matter? Do the connectors matter (gold-plated, etc)? Will surrounding fixtures or appliances such as lamps using lightbulbs, wired phones, smart phones, radios, other AV equipment, etc cause any sort of interference? What can one do to effectively produce the cleanest (best-sounding, with no interference) possible PC to DAC/HeadAmp setup?
And I thank you.