TOSLink was only designed for 96k and that’s all the most common TOSLink transmitters and receivers are speced for. On the other hand when you exceed the speced bandwidth you may just get a sloppier signal: for example, one that’s got more jitter and/or less amplitude. With a TOSLink cable that doesn’t compound these issues too much it may still work just fine. I’ve seen some that work at 176.4k but not 192k. Also I’ve seen some sort of work on faster signals but introduce enough errors to sound “fuzzy”. If there’s any suspicion of errors you might run the bit perfect test for a while and see if there are any problems, but staying in DoP mode almost surely means there are few (if any) errors at 176.4k.