Playing 7.1/6.1 tracks on a 5.1 system

[iamkoza]

Question for you fine folks.... I can't seem to find an answer anywhere.

I use a PS3 as my blu-ray player. I have an Onkyo TX-SR705 receiver which is properly configured for a 5.1 system. My PS3 sound settings are set to auto... so the 7.1 sound options are checked. When I watch a 7.1 or 6.1 soundtrack, my PS3 sends that to my receiver. I know this because hitting display on the receiver confirms it (for example it will say MCH 7.1 for multi channel 7.1). Since I am sending it via LPCM, am I to assume my receiver is not touching the sound and I am losing the two back channels?

I would go in to the PS3 options and uncheck the 7.1 boxes, however I've found that it screws up the sound options on other games. I don't want to have to tinker with the ps3 sound settings every time.

I just want to confirm that my receiver is down mixing things to 5.1 when it receives a signal that is 6.1/7.1. Is there a way to test? thanks!