I have a 5.1 Surround Headset (Speedlink Medusa NX) which is plugged in to my 7.1 (I think) Onboard Sound card. The Headset does have a USB plug, but I think that one is only used for getting electricity.
My computer also has some front jacks which are working perfectly fine. My normal speakers are plugged in here.
I can't see my Headset in the "System Settings -> Sound -> Output" area. It is weird, but I can use the Microphone of my headset. In the "System Settings -> Sound -> Input" area it is called "Rear microphone" and works. I also have a "Front microphone" there, which probably refers to the front jack.
I am fairly new to ubuntu and thus don't know the terminal commands to give you any further (useful) informations. If you need more details, please also describe how I can get those informations.