My guess is that there is an audio setting somewhere in the 830 that allows for DD5.1 output. Note that SD channels are typically DD2.0, while most, but not all, HD channel programming is DD5.1. Here's the FAQ on the topic:
Sometimes there is a firmware handshake between devices that may provide say PCM if the connection is directly to a TV instead of an AVR. Direct connection to an AVR should provide for DD5.1 signals to that AVR (when available), but manual intervention by the owner may be necessary in the audio settings of the STB itself.
As discussed in the bolded part of the FAQ, if you attempt to go "through" a TV with the audio signals to the AVR, then the TV can sometimes limit the signal to PCM. Again, a direct connection to the AVR via HDMI or a digital audio cable (optical or coaxial audio) should provide DD5.1 signals when available in programming. Also, most, but not all, newer TVs have audio settings which allow for DD5.1 or similar setting like "bitstream/raw" if you attempt to go "through" the TV.