it's working fine now
The problem started when I tried to increase the volume with my Harmony remote from another room. At 1st, nothing happened, then it suddenly topped out. I tried to get it down with the remote, no dice.
I ran from the kitchen to the family room and manually turn it down, which worked, but then it didn't go up. I turned it off, waited a while, the volume would go up a little and then on it's own go back down back to 0 (or, according to the dial, - 80). Turned off, turned on, repeat, same problem.
left the house, came back a few hours later, just for kicks tried it again and it's fine.
I also was afraid that going to full juice would have blown a speaker, but fortunately it didn't.
I guess something temporarily shorted and then fixed itself