Are shorter digital cables better ?
Yes. Because you get fewer reflections within the cable, hence, less jitter in the data stream. Data jitter is audible on good playback systems, it is also cumulative, i.e. it adds up with every generation. Using a hard drive on a computer to reclock the data to a DAT machine will reduce the jitter to the level of the clock jitter from the computer I/O PCB. The data is loaded onto the hard drive then written back to tape, a simple jitter reduction method !