Doug, I should clarify my earlier comments about digital cable length by adding that they only pertain to electrical (non-optical) S/PDIF and AES/EBU cables. My comments don't apply to USB cables, in part because the risetimes and falltimes of USB signals are vastly different than those of S/PDIF and AES/EBU signals. As I had mentioned, and as further explained in the paper I linked to, signal risetimes and falltimes are key variables affecting what length will be optimal.
Also, I'll add that if a very short length is practicable, such as perhaps 8 inches or so, that can be expected to often be as good or better a choice for S/PDIF and AES/EBU than 1.5 or 2 meters. It is the intermediate lengths, such as 1 meter, which (depending on a complex and essentially unpredictable set of component-dependent variables), stand a somewhat lesser chance of being optimal than those other choices.
Regards,
-- Al
Also, I'll add that if a very short length is practicable, such as perhaps 8 inches or so, that can be expected to often be as good or better a choice for S/PDIF and AES/EBU than 1.5 or 2 meters. It is the intermediate lengths, such as 1 meter, which (depending on a complex and essentially unpredictable set of component-dependent variables), stand a somewhat lesser chance of being optimal than those other choices.
Regards,
-- Al