This is an interesting question - I always thought that any coax cable will outperform the TosLink interface, not to mention an expensive one. But that was before I tried the van den Hul Optocoupler mk II optical cable, as recomended by some AgoN members. To my surprise, when put between Theta Basic IIIa DAC and Marantz CD 63 KI player, the Optocupler outperformed the far more expensive Illuminations D-60 coax. I wanted to try it also between my dedicated Theta transport and theta DAC, but unfortunately, Theta transport lacked the TosLink output.
Anyway, IMO the Optocoupler is a great alternative to any coax cable, and it cost less than 100$.
Anyway, IMO the Optocoupler is a great alternative to any coax cable, and it cost less than 100$.