[lubuntu] USB M-Audio Fast Track as USB Headphones?

I own a Dell Vostro 1700, vintage 2008. I recently installed Lubuntu 15.10, to help the old girl cope with the reality of age. However, to my chagrin, I can no longer use my M-Audio Fast Track recording interface as a USB headphone jack, as I used to on Windows (my standard headphone jack fried itself around 4 years ago, and replacing the part did nothing to fix it). Any insight on how I can easily configure Lubuntu to route my system audio through the USB device?

Any help would be greatly appreciated.