See my white-paper:
http://www.positive-feedback.com/Issue14/spdif.htm
We can argue til the cows come home about the signal risetime and whether this is really necessary, but I have verified it using a 400psec risetime device when doing jitter measurements. (Most S/PDIF outputs are much slower than the gear I design, more like 4nsec) I either have to connect the device directly to the scope or through 1.5m cable in order to avoid adding more jitter. It shows up in the plots and the numbers.
Attached is one independent A/B test, albeit not controlled, that confirms my claims that 1.5m is better than 1m or 0.5m length.
http://www.positive-feedback.com/Issue14/spdif.htm
We can argue til the cows come home about the signal risetime and whether this is really necessary, but I have verified it using a 400psec risetime device when doing jitter measurements. (Most S/PDIF outputs are much slower than the gear I design, more like 4nsec) I either have to connect the device directly to the scope or through 1.5m cable in order to avoid adding more jitter. It shows up in the plots and the numbers.
Attached is one independent A/B test, albeit not controlled, that confirms my claims that 1.5m is better than 1m or 0.5m length.