If you set it up correctly you will get DD True HD and DTS-MAHD via analog. I'm not sure if you looked at gonk's set up link for the 83 but you might want to refer to it and make sure you've got things set up correctly:

http://prillaman.net/setup-970bdp83.html

Not sure why you've got your tv out to the 970 instead of the cable box directly in, but if you follow the instructions above you'll be fine.