for every app... that would be nice, but KMplayer would work for you since it has dual renderer options. Just leave your pc speakers at default and for the KMplayer set the HDMI output, and your wifey will get her sound....
I on the other hand... (don't mean to steal your thread or something

)... Want to find a way to sync those two renderers (first being realtek HD, second ATI HDMI).
I have four old pc speakers and two HDTV speakers I've tried to set it to be 6 speaker system and KMPLayer does play same source audio thru two diferent renderers, but there is an half a sec diff, what sounds like an echo....
If you know how to fix that that would be nice....
either way... hey good luck.