Well the "tech" is a knob, lol. As for HBOHD, ShowHD, HDnet, etc, yes they should carry the DD signal. Not every show on Discovery, HBO, Show are in DD but a majority are. I'm not sure if this will help as all STBs are different. Did you try running a coaxial/tos link cable for the audio along with the HDMI for video just to test the audio signal? Or possibly you have a defective STB? Try getting a replacement box especially if it is the 811. Maybe you can get them to send you a 211/411 when they are available.
As for cancelling, you're pretty much stuck, Dish only allows 3 days and then your stuck in your contract. Don't throw in the towel yet as it may cost you a small fortune in penelty fees.
