Many TVs will not pass 5.1 if the source is HDMI. So set you Roku to send stereo that all the TVs I know of will pass.
Just upgraded to Roku 3 (from RCA) and am trying to hook up to existing Comcast cable box and Panasonic Home Theater. I am able to get a picture; however, the streaming channels' (Netflix, Hulu, etc.) sound can be heard through the TV speakers only -- not the Home Theater Sound System. Cable TV and DVD's will play through Home Theater.
The cable box, Panasonic Home Theater and Roku are connected individually to Sharp Aquos HDTV HDMI inputs. What must I do to play streaming channels through Home Theater. I was unable to get an answer from Roku.
Thanks in advance for your help!

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic