I have some (imo) nice logitech x-620 6.1 speakers and a k7vmp mobo. I wanna try to use the 6 channel (5.1) onboard audio, but there are only 3 slots. One green (front) one black (sub) and a mic slot…..Where do I hook up the orange cable? I think it should be possible. Also, since most music doesnt use all 6 channels,  how would I duplicate sound produced my the front speakers?