The SPDIF out is a pure digital signal from the Kronos synthesis engine. On the other hand, routing through the audio inputs on the Studio 192 means that the pure digital signal of the Kronos is converted to an analog audio signal at the Kronos Digital to Analog (DAC) Output Converters then that signal is sampled at the Studio 192 Analog to Digital Input Converters. Even if you sample at 192khz, The DAC and ADC stages are going to introduce artifacts and distortion. This might give your signal more character, but if you are going for the cleanest, purest signal, use the SPDIF.
