"Meaning that yes, comparing Optocoupler MKII to that of a generic (yet decent) Toslink cable reveals that the Optocoupler does offer better sonics. Why? Got me… just passing the bits along, though perhaps it is doing a better job of it with less hassle. Don't know. But the Optocoupler MKII audibly offers greater presence, dimensional palpability, harmonic rightness, etc. All those things we associate with higher levels of resolution and having the right information at the right time, though the Optocoupler MKII does this without going over the top. That is, the Optocoupler MKII is not brash or bright… no grit or glare. Just sweet music that is not euphonically overly colored and possessing of proper delicates that are oh so delicate. It simply sounds quite right."

Dave Clark
Positive Fedback Issue #39 / 2008
 

"Both Van Den Hul Optocoupler and WireWorld SuperNova III+ hold their own against far more expensive non-optical (blind?) RCA-S/PDIF cables. The differences that do exist don't proclaim one or the other the victor based on clear superiority. They simply operate inside system compatibilty effects and those of personal preferences. And true, "bad" Toslink does most certainly exist. If it's bad, it's clearly bad."

A Digital Interface Comparison: Toslink vs. RCA
6Moons, unknown author
November, 2002