Well, i did find one thing that COULD work, but it really depends if you want to spend a chunk of money to MAKE it work. It also does assume your sources are HDMI.http://www.atlona.com/Atlona-HDMI-DVI-Scaler-with-Analog-Digital-Audio.html
If you are using HDMI, you can use an HDMI to DVI & Audio conversion unit. This box takes a single hdmi, and outputs a DVI/HDMI, and Standard Left and right audio, which would go to your bose system.
If you search around the web for the model number, i've seen them as cheap as 149