I suspect that differences in SQ when changing cables or sources on S/PDIF can be heard in DACs with low J test jitter. I just don't put much stock in this method. I have yet to hear ANY DAC that is immune to jitter on the S/PDIF input.
The B/W of AP equipment is insufficient to do direct jitter measurements. I need the 7GHz scope.
I like to think outside the box. That is what sets my products apart from the pack.
Steve N.
Empirical Audio