You mention DSD again.
You cannot send DSD over S/P-DIF, neither coax nor toslink.
Edit: also, the iDSD will not convert DSD to PCM. If you want to use your external DAC, you can only play PCM files.
I'm really Sorry i don't understand you,
If i want use audio file that i mention before like DSD,192k with my AK120 and iDSD? What i need to use cable mini jack to mini jack or what
iDSD supports DSD - YES
AK120 supports DSD - YES by conversion to PCM
Toslink supports DSD - NO
Coax supports DSD - NO
USB supports DSD - YES (using compatible drivers)
Clear?