I recently bought a surroundbar 4000, hooked it up and after a few minutes the volume starting increasing on its own. I had to shut it off and turn back on to gain control again, this happened a few more times within 10-20 minutes I finally shut it off and called Polk tech support. I was told probably a bad amplifier and to return for a new one, which I did. I hooked up the new one and went a few hours before it started happening again. I tried all the trouble shooting I could think of. changed the channels, blocked the IR receiver (in case a signal was coming from outside source) I am connect to a Samsung P550 series tv via the optical out. any advise?