IMO, it's not worth the extra headache of using SPDIF for your audio from the Kronos. Maybe it's because I have too many synthesizers and the cost of doing SPDIF input for all of them would be mind blowingly expensive, but I've found that I have next to no noise when just using the Analog outs from the Kronos into my Audio Interface (Saffire Pro40). I even run the outputs through a patchbay and have no issues.

My Kronos audio is connected via S/PDIF to a digital autio I/F and the keyboard is controlled via the Korg midi drivers. That works absolutely stable for me - with no losses on audio quality.
 
If I am not wrong, than a PC can support one ASIO driver at the moment only. We can not run two or more in parallel. Having more than one synth in the setup a multi-line-input audio interface is required for us PC-users anyway ...

SoundRaider
 
 
If I am not wrong, than a PC can support one ASIO driver at the moment only. We can not run two or more in parallel. Having more than one synth in the setup a multi-line-input audio interface is required for us PC-users anyway ...

That's totally correct. Until you can transparently merge multiple audio devices natively in Windows (kind of like you can on a Mac and in Linux), to me, the Kronos is pretty much useless as an audio interface, because of the limitations of it.
 
Microsoft has made the attempt to offer the framework since Vista (WASAPI) to improve low latency audio on Windows, but from what I've seen of it, hardware vendor support is not very good (my pro40 works, but only 1/2 the ins and outs show up) and it doesn't support device combining. If those 2 things could be addressed, I would use that instead of ASIO in a heartbeat.

Analog output from Kronos sounds great. Why not just send that to a USB mixer or interface and forget about all those compatibility issues like driver types, sample rates or latency? Or you can just create a WAV file mix from Kronos onto a thumb drive and import that into your DAW.