I'll chime in on my bad experiences with the Sound Pro's optical cables. First I ordered a RA toslink > RA toslink. DID NOT work with a Radio Shack toslink>mini adapter while connecting my UA-5 to my jb3. So I called Sound Pro's and swapped it for the RA toslink > RA mini. That also DOES NOT work with the UA-5 / jb3 combo; all kinds of static and dropouts.
FWIW the 3 ft. toslink > toslink Radio Shack optical cable with Radio Shack toslink>mini adapter has worked PERFECTLY countless times.
But due to the many others that have had good experiences with Sound Pro optical cables, I believe it has something to do with my own gear.
So if anyone knows of another RA toslink > RA mini optical, lmk because I'd like to try it out...