SQ depends on a number of things and is not really relatable to the khz rating. A higher khz rating doesn’t equal better sound. I don’t find a difference between them, but, generally, I use Coax SPDIF over Toslink.
Once again, SQ is all in the ears of the beholder. Everyone has an opinion, none are definitive. Toslink by specifications has a limit of 24/96. Some implementations CAN go to 192. USB usually has a higher khz specifications. What is the DAC you are using? Some DACs sound/function better on the different inputs.
An OS will support whatever the device driver will allow. In Windows, you would load the driver that comes with the DAC, usually an ASIO driver and that will operate in exclusive mode at the limit of whatever connection specification is allowed by the DAC’s connections. So, if you are connecting it via USB it will be 32/384. I run at 32/384 and DSD256 native mode all the time.
Linix is similar, however, manufacturer’s usually do not make Linux driver, so you have to use the base ALSA driver. In PCM mode it should be the same as Windows + Manufacturer’s driver. However, if you go to DSD while you will get native mode with Windows + manufacturer’s driver; you might not with Linux; as it then depends on whether or not that specific device has been patched into that specific Linux distro.
ROCK is a closed Linux variant. So, it uses ALSA as well.