Don't know if anyone will  know this or not, but my Panasonic TC-P60U50 plasma turned on with distorted sound this morning. It was bad through my sound bar, but it's worse, when I turn the speakers in the TV on. Even at volume level 1, the sound is VERY distorted and loud. The sound bar seems to be able to mitigate this somewhat and, while it's not very loud, the audio sounds like it's being sourced from a very high input (and I assume this is exactly what is happening).

This happens from input through either of the HDMI ports or for OTA broadcast through the tuner.The sound bar is connected through optical.

Main board? I have to assume that's the most likely culprit. I see I can get one for ~$35. I'm tempted to go this route, because I really don't want to buy a new TV right now and this one still has a great picture, even if it isn't 4k capable.