While I do agree it should be implemented in the audio mixer so that one could simply assign any application wherever they want (drag and drop in the mixer ftw 
), I don't think that's going to happen ever tbh (one reason being that the main application people think of this for is media players [music/movies] - and many prominent media players have this option already haha).
And in regards to this, posts from years ago (quickest example [google search] shows a reply in 2011 on superuser.com where a user wanted to effectively do this with miscellaneous games) show that this is a longstanding issue that hasn't really gone anywhere over the last several Windows OS.
On a side note, I would totally donate $20 to the cause of getting this option in Dolphin
EDIT:
@Jhonn https://forums.dolphin-emu.org/Thread-audio-playback-renderer?pid=326141#pid326141
I see I didn't search hard enough. Found what you were referring to I think:
http://code.google.com/p/dolphin-emu/issues/detail?id=5976 (post number 3 on this page by "Montisaq...@gmail.com") dated Feb. 4th, 2013.
), I don't think that's going to happen ever tbh (one reason being that the main application people think of this for is media players [music/movies] - and many prominent media players have this option already haha).And in regards to this, posts from years ago (quickest example [google search] shows a reply in 2011 on superuser.com where a user wanted to effectively do this with miscellaneous games) show that this is a longstanding issue that hasn't really gone anywhere over the last several Windows OS.
On a side note, I would totally donate $20 to the cause of getting this option in Dolphin
EDIT:
@Jhonn https://forums.dolphin-emu.org/Thread-audio-playback-renderer?pid=326141#pid326141
I see I didn't search hard enough. Found what you were referring to I think:
http://code.google.com/p/dolphin-emu/issues/detail?id=5976 (post number 3 on this page by "Montisaq...@gmail.com") dated Feb. 4th, 2013.