Multichanel Sound playing in external usb sound card

I work with a modified version the ofSoundPlayer that can select the needed device and can also select how many outputs are needed. I use 4, 6 and 8 channels.
Actually it is mixed with my own work, but I could make an addon. I cannot try it before saturday because my soundcard in in another place.
What do you exactly want to do, and for what kind of projet ?