Unfortunately, my headphone jacks recently broke, and I will need to get the motherboard replaced. In the meantime, I was trying to find a way to manually change my speaker settings from outputting to headphones to the built in notebook speakers. I have a Studio XPS 1340 if that helps.

http://en.community.dell.com/support-forums/laptop/f/3517/p/19354775/19790501.aspx#19790501