Make USB non-default

[Intel_Hydralisk]

Just got some usb headsets. Currently when the usb is plugged in, it overrides the 3.5mm jack (that my speakers are plugged into). I was wondering if there was a way to make it go the other way around. I tried setting the speakers as the 'default device' in Windows 7 but it won't switch to the usb headset even if the 3.5mm has nothing plugged in.