Digital out being strange

[rbrook]

Playing with the playback settings in Vista using my X-Fi digital out and i've noticed that when set to digital out as default sound output i get small crackles (and the error light on the DAC lights up briefly) when it plays a sound fine listening to music as you hardly notice the quick crackle at the start but flicking through folders or anything that plays very short sounds it gets really annoying. but if i set the default device to be the speaker outs on the X-Fi the problem goes away and the digital out still works.
I think I'll just leave it set to Speaker out then, any ideas as to why and any tips to maybe improve things more.

Richard.