I have a Kindle Fire HD 8.9", last year's model, connected to my Pioneer AVR with HDMI. I just watched an episode of Game of Thrones, which I understand is shot in 5.1. The DD/DTS lights on the AVR did not light up.
When the AVR is set to Auto Surround or Direct mode, I only get audio from the front two speakers. But if I set it to Dolby Pro Logic mode (which is disabled when listening to a 5.1 source, indicating that this is a stereo source), much of the sound is transferred to the center speaker, including the dialog. The front L/R speakers still output distinctly different channels, especially when playing music, and the surround channels have a bit of light ambiance.
So... does HBO Go for Kindle Fire actually provide a proper Dolby Pro Logic track, or is my receiver just upmixing a standard stereo track and being rather clever about it?