I don't know about your Panasonic, but my TC-P50S60 uses different video settings on each input. Meaning, HDMI 1 would be set to video gaming while HDMI 2 would be set to Cinema. Even the professional adjustments are different on each of the HDMI inputs.

I would recommend setting it up where the gaming system is on the HDMI 1 and AVR is on HDMI 2 if your AVR supports ARC (Audio Return Channel). Say if you are playing a video game and what great sound through your AVR. Just hook it up like above, and set your AVR to accept the ARC and the audio will be sent back to the HDMI that it uses to "output" from the AVR. With this set-up, you have only one cable from your AVR to your TV.

KOT