I am a DSJ owner. From the cheap seats:
I can;t tell a difference in cables or cable type into the Junior. Others swear this matters, but not me. As Ted alluded to above, optical cables vary in their ability to pass high frequency so YMMV.
Given your SACD player, and I assume a computer, you have a wonderful opportunity to compare various versions of the same recordings via multiple paths… have fun!!! A bit of a warning… if your source material, of the same tunes, came from different sources or purchased at different times, the povenance of each may be very different and the convesion/mastering/et al… may be different resulting in poorer sounding music from what should be a superior format. So be careful when you conclude that one type of hookup is better than the other.
Check this thread out for new owners of DirectStream, you may find it helpful: New DS owner, share your experience of the dac running in from new?
Peace
Bruce in Philly