Yeah, this is definitely a case of the TV only converting the HDMI audio to stereo, and not passing it along to the output in the daisy chain. That kind of sucks.

I'm able to 5.1 digital audio on a few of my devices by routing their optical and coax digital outputs directly to the stereo. The problem is that the stereo doesn't have enough inputs to do them all. So a couple of my devices, I only get stereo instead of getting 5.1. Ah well.