I'm curious about how a $100 Toslink cable can "sound" different than a $10 one. I understand how important the speak cables to sound. The analog signal is changing when transfered through the cables. Transfer digital signal is whole different. It's like wire transfer money if you think off transfer analog signal is like carry the money with a bag. You may loss money if the bag is leaking more leaking means loss more money. But for wire transfer, how big the mistake is not depends on how many numbers you misspell, a single digital mistake can result in 1 cent, 1 dollor or a billion dollors difference. So, error is not allowed at all, the receive end must verify (verifiable is one of the good thing of digital), request-resend-if-error and cache (so it has time for verify and resend) the information. It's true that cable could be low-loss or high-loss because of the cable quality, but that is just why verify-cache is important, ultimately, there should be only the correct digitals in the cache ready for processing.
As all the Toslink manufactors declare their good cables produce clear, full and richly detailed sound. I wander how a bad cable can selective drop those digitals that make the sound rich.