I connect to a Canton DM 9 Soundbar via TOSlink, and I hear that crackling and occasional dropouts only with FLAC, not with MP3. Any settings I’m missing?
Hi @thobu,
please, check your audio settings at settings -> system -> audio and set them to the following:
Audio device: PCM
Number of channels: 2.0 (S/PDIF only supports 2 channel LPCM)
Output configuration: Best match
Passthrough: enabled
DTS/AC3 passthrough: enabled
DTS-HD/TrueHD/E-AC3 passthrough: disabled
AC3 transcoding: enabled
And keep in mind to disable “sync playback to display” under settings -> player -> videos for passthrough to work.
If you want your TV’s refresh rate and resolution to adjust according to the source’s frame rate and resolution, also set "Adjust display refresh rate” to Always or to On start/stop under settings/player/videos.
If that should solve your issue, inspect the current Toslink cable, try another one.
after some testing I found out that I have these issues just with some FLACs
Didn’t you have the broken Toslink socket flap? And isn’t your Toslink cable only stabilized with tape?
FLAC files that have more than 16bit/44.1kHz need more bandwidth than decodes of MP3 (which are only 16bit/44.1kHz). So, the dropouts are most likely connected to an unstable connection which is caused by the socket being broken. That would be my guess. Are those few FLAC files hi-res encodes with more than 16bit/44.1kHz?
I have the same issue when passing 24bit/192kHz FLAC to my amp via Toslink as it requires the cable to be aligned perfectly straight inside the Vero’s and the amp’s socket - the bandwidth needed is very high and therefore the whole setup is very intolerant to not straightly aligned plugs (keep in mind that Toslink was originally not designed for more than 24bit/48kHz audio and didn’t transport more than 24bit/96kHz for a long time, even today a lot of equipment can’t process 192kHz via Toslink). This intolerance would most likely be noticeable for you with even less bandwidth hungry material as your Vero’s Toslink socket is not stable at all. 
Very likely, seems I have to apply your recipe sooner than later … 
Just check your files and see which bitdepth and samplerate they have… It would give a first clue. If they’re more than 16bit/44.1khz or even 24bit/192kHz, it’s most likely that the socket is the issue here.
I’d definitely recommend that
the crackling ones are 16bit/96kHz
And the ones which are fine 16bit/44.1kHz or at least less than 96kHz?
yes
Ok… That is hinting towards my idea. Does the crackling change or even go away when you move the plug slightly?
it’s not easily accessible but based on what you assume I’d think so - will try it later
Would be good to test this… If it’s not there in certain positions, it’s definitely the socket.
I can confirm that the crackling stops!