Do these Bose speakers have a headphones port, and does your computer have a blue line-in port? If so, you can record the speakers that way, choosing the Realtek line-in input, but this depends if you can stop the headphones port shutting off the sound to the main USB speakers.
Or you can try Total Recorder from http://www.highcriteria.com/ . It is a free trial and also has a Windows WASAPI loopback recording choice.
I also suggest you could post the contents of Help > Audio Device Info… top right of Audacity.
Gale