I also own Kii three.
Streaming Qobuz 99% of listening time.
First streaming device was a Daphile PC via USB, good but no magic
Daphile PC > USB/spdif converter ( good, perhaps better ) again no magic
Auralic Aries femto with Linear power supply, good+, no magic via USB or Aes or coax spdif
I found in the cellar a 20 years old device named Monarchy Audio DIP. It’s a spdif reclocker. It’s limited to 44khz, 16 bit.
On the Aries i set CD quality ( of course no Hires )
Magic: Kii are are really a very revealing audio system, but what you get into is strategic.
Magic means more music: every song is listenable, bass is when bass is, voice is beauty, dynamic is palpabile. Music has body, when there is body in the master. Live records wow. No glare, no greyish.
So Dip Made a miracle? Yes a small, but miracle.
consideration: Auralic femto, despite the name is jittery; Kii input circuits , as good as they are, aren’t able to govern a jittery source.
My CD transport, Philips based, is a very good spdif source and the amelioration by Dip is marginal, indeed. I worked the spdif output as Lampizator explains. CD sound very, very good.
conclusion: if you have a system like Kii, in which the Dac is integrated, you have to work to input a spdif source that is the least jittery possible.
If you want remain with PC as a source you can try modern usb/spdif converter ( Singxer, gustard, denafrips).
I stay with Auralic because the software is very good. Next move is a Mutec mc3 smart clock ( spdif only reclocker )
There is also a Mutec version with usb in that can fit your needs.
Greetings.