Siberia Elite Headset is really quiet

I have the Siberia Elite Headset and it comes with a usb sound card. When I use the usb sound card the headset is really quiet compared to using my onboard sound. 

Does anyone know if there is a way to make them louder using the usb sound card ? 

Before anyone says just use the onboard sound, I want to use that for my speakers. I also don't want to be plugging and unplugging things. 

I also want to be able to use the software that comes with the headset so using the usb sound card is a must