ok i also had struggled for this... but its relatively easy...
first u have to make sure your sound card supports dual streams...
my motherboard is the DX58SO do its sound
driver is realtek AC889
intel made it possible from these versions onwards.. i think 880 onwards..
so inly if your card supports this u get an option in "sound manager".. above the "folder like icon" at the upper right part of the screen window. "device advanced settings"
upon clickin this.. under playback devices.. u get the following option..
"make front and rear output devices playback two different streams simultaneously"
after clickin on this it separates your streams and u get two icons appearin "HD audio 2nd output" and "speakers" the 1st is the front panel and 2nd is the back panel...
after youve managed to do this.. find an appropriate application to make use of this..
there are very few.. one of them which can use these streams in "media player classic home cinema"
View -> options -> output ->direct show audio -> select output stream..(2nd audio output or speakers) then restart the player and then it outputs the audio to the one u selected.. other applications like windows media player, vlc, power dvd, all push their streams to the default output.
Hope this helped