[LAU] How clean is direct digital out

I have this onboard audio "card" and snd-rate shows it does 44100-192000 on playback (perhaps capture as well)... nVidia Corporation MCP67 High Definition Audio (rev a1) My question is if I playback a 44.1 khtz CD track out through the S/PDIF on the motherboard will it be modified in any way or would the values from a CD, mp3 or wav pretty well go directly out the S/PDIF ? The reason I ask is that the analog audio output is medicore (but better than previous onboard audio I have had access to) but perhaps the optical S/PDIF out would be as good quality as any high end card (seeing the MCP67 handles 44100 natively) ? --markc