For the digital cable, try to get a true 75 ohm cable. Most are not, and frankly RCA plugs are not 75 ohm (its a stupid standard, get BNCs!, ok rant off) It must be intended for digital or will distort the threshold crossings that determine timing. fo he analog side, its....analog. So the same rules you apply to RIAA, preamp-power apply.
Yea, cables matter. Unfortunately its often because engineering is ignored and not in a good way.