If you are using toslink/spdif out of the computer into a processor then you are using the DAC of the processor.
The signal to the processor is pure digital, the DAC of computer does not come into play.
With a good quality optical/coax cable there should be no loss.
The signal to the processor is pure digital, the DAC of computer does not come into play.
With a good quality optical/coax cable there should be no loss.