I've just bought the same setup, and I must admit I'm not yet confident enough to play around with the core settings yet. Need a week to read the manual !!
To plat safe, I have connected the 320 to the 1910 with an HDMI and left all connection settings at HDMI or auto. I have played several BD movies now, but only 1 was HD audio (Blade Runner) and lit up the blue HD audio light. I did check the audio settings on the other movies, but none were listing an HD audio track.
SO - just because you are playing a BD, don't assume it is HD audio as well as HD video. It's not just the older movies either, I just watched 'Fool's Gold' on BD - great location shots. It's a newly released movie, but still didn't have an HD audio track.