Whether you can hear a degradation depends on how well the cables are terminated and whether the connectors and cable is 75 ohms etc.. If everything is matched perfectly, then the cable length is less of an issue. It is when there are reflections on the cable that the length comes into play. Most S/PDIF outputs are not 75 ohms, but most S/PDIF inputs are 75 ohms. The cables and connectors vary a lot.
The comparison to an analog cable is not a valid one. Transmission-line effects on an analog cable are usually inconsequential or have small impact. The same effects on a digital cable can make a big difference in jitter.
The degradation is a lot like the sound of jitter. It is high-frequency noise layered on the music that can be described as echoes, halos or sibilance. I do a demonstration at CES each year and most people dont hear anything until the jitter is gone. Then they realize what they have been missing and what the noise is that they have grown accustomed to listening to.
Steve N.
Empirical Audio
Manufacturer
The comparison to an analog cable is not a valid one. Transmission-line effects on an analog cable are usually inconsequential or have small impact. The same effects on a digital cable can make a big difference in jitter.
The degradation is a lot like the sound of jitter. It is high-frequency noise layered on the music that can be described as echoes, halos or sibilance. I do a demonstration at CES each year and most people dont hear anything until the jitter is gone. Then they realize what they have been missing and what the noise is that they have grown accustomed to listening to.
Steve N.
Empirical Audio
Manufacturer