I'm assuming you have surround sound speakers w/ a sub connected to the Yamaha? If so, you could use the following connections to get the ball rolling on 5.1, as well as the better lossless audio codecs from your fave blue ray titles.
Moto box (HDMI out) -> (HDMI in) pn58a550
Moto box (digital optical out) -> (digital optical in) Yamaha rec.
3600 blu ray (multi channel out) -> (multi channel in) Yamaha
"" "" (HDMI out) -> (HMDI in) pn58a550
Let us know if it works. Enjoy!
i jut purchased a pn58a550 along with a 3600 blue ray. i currently have a comcast hd motorola cable box and a yamaha htr-5560 av receiver. i have two hdmi cables one from blue ray to tv and cable box to tv. i also had a optical wire from receiver to tv but am pretty sure it only provides 2 channel sound. how in the heck do i get 5.1 sorround. i tried optical to receiver but no sound and when i hooked optical to cable box there was what i think was 5.1 but when I tried to play blue ray no sound. maybe i can't get 5.1. any help will be appreciated.