Originally Posted by Lifter
The switch does not have the capability to downmix to stereo. Your source device is what's doing that. It sees a stereo TV and decides it will only output in stereo mode. Some source devices do this (I know, it sucks - I have an Xbox 360 which does it) while other source device let you manually decide what type of audio to output regardless of what it's connected to.
Try bypassing the switch. I'm willing to bet you'll still have the same problem.
I did that with Monoprice 2.0 back when. Bypassing the HDMI switch made the 5.1 go right through. The problem is the bitstreamign the advanced audio codecs through the switch. I don't know if it's the switch or if it's the HDMI-HDCP handshake protocol that's the issue. I tested it on the following:
1) TivO Series 2 HD DVR (5.1 dolby via HDMI converted to 2.0)
2) Panasonic BluRay (DolbyTrueHD converted to 2.0)
3) Pansonic DVD player w/HDMI outputs (DD 5.1 to 2.0)
These were running to a Denon 3808ci, so there was no stereo TV in the mix. I tried difference inputs,outputs, Denon Settings, etc., etc. Going direct to the Denon passed the audio codecs no problem. The monoprice switch was the culprit, somehow.