JChin, I appreciate your responses!
They are actually three different brands of HDMI...Monster, one was a generic HDMI supplied by Comcast, and another was a High Speed HDMI from Monoprice. All three work correctly on all components (yes, i tried every HDMI with every component individually).
The equipment is plugged into a surge protector, and last week I did try removing that from the equation. I even tried running the cable to different outlets on different circuits, hoping for SOME kind of A-HA! moment.
To give you a quick summary:
--when source such as cable box or Xbox (or even a coaxial cable for that matter) goes directly into TV, i get slight pops and distortion...its consistent, usually the right channel of the TV speaker, and during busy audio the center channel on the TV crackles, like its just too much signal to process.
--this behavior is reproducible when the receiver is hooked up properly. I tried every combination of cables, components, etc to try to isolate the problem, but again it seems to be originating at my tv. Turning off TV speakers does not help.
--the tv manual suggests the recommended setup for a non panasonic receiver is running a digital optical from the OUT on the TV to the IN on the receiver, which i've done when i realized that the purely HDMI setup wasnt working. It also suggests running red/WHITE audio cables from tv PROG OUT to AUDIO IN on the receiver, which i've done. Seems to help somewhat with the xbox sound issue, but not with the Motorolla set top box issue.
--BluRay plays beautifully, sends LPCM signal to receiver and I get perfect sound. The BluRay and Receiver are both Sony. TV Panasonic, Xbox is MS obviously.
I'm at a loss! I've spoken with coworkers (electrical engineers and audio-nuts) and they are gravitating towards a hardware problem in the TV.