My friend RhythmAce4218 uses this umbilical cord on his RA Opus21 and was very impressed with its effect. Hopefully he will share his findings...if I see him in the next day or so I'll suggest he join the thread.
I have not been able to do an A/B comparison of the cable so cannot comment, but since he added the RSAD umbilical and had the GNSC ref mod, his system has never sounded better to my ears. Hopefully Darrin will comment on the relative contributions of both?