I am also wondering if anyone has had this issue with the 10.33 (WM8741 chip).
One thing that might help is a cheap toslink-coax converter. I run an optical through my TV to my AGD DAC and it would cut out (don't know why). I had a Monoprice converter not being used so I tried that, seems to work now without cutting out.
Also, I have discovered that not all optical cables work as well as others, some seem to hold signal better (for lack of a better term).