there are too many permutations to go into here but the jest is this:
Depending on the codecs and where the decoding is actually happening, TV's can sometimes downgrade audio that is being sent out to a receivr. It could be something in the settings of the TV, or the Xbox or the receiver.
The ideal way to handle surround sound is to send all audio in bitstream form via HDMI to a receiver to let it do the decoding internally. The video then goes out via HDMI to the TV. Since your Receiver has no HDMI inputs you will have to go through the TV.
The only advice I can really offer is research the limitations of HDMI and optical cables and go through the settings on all your components to make sure they are treating the signal the way you want it to.
Also, be aware that the Xbox 360 has a known HDMI glitch where even though games are available in DD 5.1 it will send the signal out over HDMI as stereo. Sometimes you have to go in and reset it to DD 5.1 several times in a row as it keeps reverting to stereo.
i have a sony receiver (str-k790) and a sony lcd bravia tv (kdl-52s5100) and i bought monster hdmi cables to hook up to my xbox 360. and im also using an optical cable to the receiver..
Heres the problem im having, when i use the xbox component cables that have an optical hook-up on the plug itself, i get perfect sound, for example, when im playing call of duty and i throw a grenade or there is action behind me, all the channels function properly and harmoniously, front rear and center plus subwoofer.. the grenade goes off and if the action is behind me i hear the subwoofer and all doing their thing. lound deep booms from all sides. GOOD.
<component set up>
component out into the tv.
optical out of xbox component cable into reciever
BUT when i use the hdmi cables, and run the optical from the receiver to the tv, when that grenade goes off behind me( around me or sides except for the front. front works fine), that signal thats transmitted through the rear channels DO NOT get the same boom. its like the woofer doesnt get the signal or the signal isnt being transmitted correctly.. the woofer IS on because i hear it through the in game music, but when theres action behind me, the sound is compromised incredibly. no lound deep booms behind me, but when i turn around, the boom sound is back. only the actions in front get the correct signal but not the rear when im turned away from the boom.. BAD
i used MONSTER cables and xbox hdmi cable with the optional optical a/v plug so u can use the hdmi and the a/v at the same time to get the optical to run from the xbox to the receiver and not from the tv to the receiver..
hdmi out of xbox running in to the tv
optical out of xbox into the reciever AND i also tried the optical from the receiver to the tv. none work, i get the same lack of effect.
*** is wrong?? why is the sound so compromised when im using an hdmi cable that SUPPOSED to be superior?!?!? i called sony, no answers. i tried every possible configuration on the reciever, xbox and the tv to see if there was a setting i missed about hdmi hook-up.. and i got nothing.. i spent 9 hours a full wasted day and ended up defeated. i hope someone knows *** their talking about and can offer me some ideas to sooth my anger..