Spdif cable

Zavato, It is very difficult to recommend particular cable because it is not only system dependent but also sensitive to amount of electrical noise present. The difference between cables is caused by the jitter of digital signal that converts basically to noise in analog domain. There is some jitter present in transport's output but additional jitter can be caused by either electrical noise coupled into system (transmitter, receiver or cable) or reflections of the signal in the cable on impedance boundaries. There will be no reflections if characteristic impedance is perfectly matched but it is never the case. Noise pickup can be reduced by good shielding of the cable and reduction of electrical noise (separate outlet, power supply filter etc.) Reflections in your cable can be reduced if you keep cable very short or a little longer than 1.5m. Rule of thumb says that reflections appear when propagation time of the signal is more than 1/8 of transition time. Transition in typical source is around 25ns making required propagation time 3ns. Since signal travels in cable about 5ns/m it results in about 2ft of cable. I would make it less than 1ft since electrical connections inside of electronics also count into total distance. If you cannot keep it <1ft make it more than 1.5m Jitter is often caused by the first reflection from the end of the cable adding (affecting shape) to transition that caused it. We can assume level recognition (threshold) point in about middle of transition (12.5ns). When cable is 1.5m signal has to travel forth and back making 3m distance that is equivalent to 15ns time. It will just miss the threshold by 2.5ns.

Noise that I mentioned is proportional to the signal level (loudness) and undetectable without signal. It appears as a lack of clarity that affects a lot of things including imaging.
It is impossible to answer if you are loosing anything since jitter is always present (you can always make it better). If you like the sound chances are that jitter is negligible. Keep your power supply clean (separate line, conditioners) and reduce ambient electrical noise pickup (other cables or noise sources like computers in proximity). As for reflections - use 75ohm rated connectors (most of RCA connectors are not). Exact source impedance is unknown and that is why it is so difficult to recommend particular cable. In certain cases optical cable (Toslink) delivers better results in spite of slow transitions. It is possible to reduce jitter by reclocking s/pdif signal but it costs around $500. When comparing cables or systems pay attention to clarity of the sound.

As usual, Kijanki's response is accurate and informative. My brief response is that every digital cable I've used in my system (transport to dac) has affected the sound one way or another - sometimes dramatically.

Steakster, thank you. Your experience, most likely greater than mine, is very valuable showing practical cases. I often see technical merits in audio but audio seems to be like black magic. Your practical experience gives many people a chance to improve their sound quality.

No two anything are ever exactly the same, but in practice, I do not notice much difference using different digital cables, though it is certainly always a possibility in any particular case, especially when noise factors as mentioned come more into play.

I notice much more difference in general with analog ICs and recently even with power cords on DACs where I think noise factors are often a bigger issue.

I'd consider the effect a power cord like Pangea ac-14 designed to address source level noise issues specifically might have compared to digital IC, which is a much tougher call I'd say.