But, they're all a minimum of 3 ft. long. Which I don't want.
There are shorter length pre-made optical cables out there,but as you've found they are'nt mini-tos (3.5mm) to std. tos.
Usually one can find 'em in 1.5' (18") lengths from a couple of places (Parts Express -or- Monoprice for sure) with std. tos ends.
The catch there as was mentioned above usually one needs to use one of those adapters w/those "generic" short optical cables.
Hence, my wanting a custom length made. I'm sure there's some shop, or someone who does this.
Absolutely there are companies that make custom length optical cables,there have been threads here about that in the past.
Lifatec is the company I see mentioned most often >>>>
http://lifatec.com/
And indeed they can build them with a mini-tos to tos configuration no problemo.
And custom made/length interconnects too.
This one is easy,lots of companies doing this,lots of threads here 'bout those too.
I usually recommend Redco >>>>
https://www.redco.com/ -or- Marketek >>>>
https://www.markertek.com/ for this sorta thing.
Undoubtedly there are countless others out there that do this as well.
Now the reason these are'nt more common is most folks would argue that USB -or- coax are the better transfer conduits vs. optical.
So as a result the market demand is'nt very high for optical cables like this,thus why custom cables are the only way to get something like that.
Even your DAC maker (Schiit) is'nt all that hot on using optical with their DAC's these days.
Me,I've had pretty good luck using toslink (optical) thus far,but I dont do hi-res @ all as I'm strictly 16/44.1.
Hope that helps.
Bret P.