I don't know about your TV but many sets do not provide audio output from their HDMI inputs. The only solution, if this is the case for your set, is to connect the Bose directly to the DVR and DVD.
Thanks txrose. The Bose cinemate has only one optical audio input. The problem with connecting the DVR and DVD directly to it is that I have to keep switching the cable manually everytime I need to switch between DVR and DVD. Also if I add any other device in future (i may add Wii) to my TV I will have keep switching between them. Ideally I want a setup where the audio should change automatically when I change the video source on the TV.
Is AV receiver an option?