Hi Timothy, I am over in Plano. Since you are dealing with DD5.1 and not lossless audio (like BluRay) you can get the same audio stream from HDMI, optical or digital coax cable. You can run your video direct from the STB to the display via HDMI and run the audio direct from the STB to the HT receiver via digital coax or optical (digital coax is the RCA type cable, not the round coax that comes from the wall). Plug it into an input on your HT receiver, tune to that input and see what the receiver saves it is receiving. That should tell you what you have and removes the display from the equation.

In theory you should be able to route the HDMI through your HT receiver and it should pull the audio stream from it and pass the video stream on to the display. But in practice this does not always work flawlessly. There are multiple issues with the switching of the audio and video signals within the chain. The only real reason for running multiple HDMI inputs to a receiver and then one HDMI output to a display is to make it neat and have only one video cable going to the display. But you are perfectly free to route the video direct to the display from every source, provided there are sufficient inputs on the display. I send video from a BluRay, my STB and an xBox direct to the display, and send audio from each of these devices to the processor. This removes any switching glitches. The extra cables don't bother me and it just means that when I switch the display inputs I also switch the processor inputs.

For your BluRay player you want to use either HDMI, or if you have 6 channel analog connections you can use those as well, to connect to your HT receiver. Either of those will get you full lossless audio. Optical or digital coax will work but you will get a slight loss in fidelity. But to be perfectly honest, unless you have a professionally calibrated system in a media room environment it is unlikely you will notice the difference between full lossless audio and what is transmitted over optical/digital coax, which is itself a higher bitrate version of normal 5.1 anyway (DTS or DD).

I didn't know about the 5.1 issue with audio alerts. Must have missed that thread! Thanks to you and kes601 for bringing it up here.

I only hear dialogue from the center channel. All other sounds are from the left, right and rear surround speakers.

Also, somewhere on the board there is a thread where if you have audio alerts enabled it disables 5.1 surround until after you reboot the box.

According to at least one Amazon reviewer and a follow-up comment, the Sony might be displaying 2.0 DD when it is, in fact, correctly outputting 5.1.

You should be able to tell what's going on by setting the receiver to a direct or pure audio output mode and then tuning your STB to an HD movie channel that you know is broadcasting in 5.1. If you hear sound only from the front left and right speakers, you're not getting 5.1 surround. If the center and rear channels are active with discrete channel info, the display is incorrect but the audio is working correctly.

It's also possible you got a bum unit. If it's under warranty, you might want to try swapping it out for another.