control windows sounds with crossfader

hello ppl,

im the owner of a hercules mk4 dj console which is doing it great using virtual dj.

but i have one little thing i cant get to work ? or dont know if it is even possible ?
we ar organizing a event where a powerpoint presentation will be used. theres sound in it. i would like to use my console to control the sound as a master.

when testing the sound is playing well through my speakers (notebook -> mk4 -> amplifier -> speakers) but i cant use the controls crossfaders to change the volume.

is this somehow possible ?

thanks for help !