No, for a SP/DIF interconnect system, RCA connectors (at about ½ inch long) are orders of magnitude better than needed. Remember that SP/DIF in the digital world is very low frequency stuff. Now if we are talking about GHz signals then picoseconds and fractions of an inch are important, but that's another world. And for a 15/44.1 SP/DIF cable shorter than lets say 30 feet (or 10 meter) the 75 Ohm impedance tolerance is about 50 to 110 Ohms. However the newer, higher speed AES 3id spec has a 5% impedance tolerance.