Usb headsets don't use a sound card, they have their own sound card included in the usb connector, so thats why you don't need a sound card, even if you buy the best and most expensive sound card, if you plug a usb headset you won't take advantage of it because you will be using the usb connector, if you want to get the sound from a dedicated sound card you need to use the analog connector, otherwise you won't.