Now I am really confused.I switched the backplates and the left speaker (now with right plates) played music quietly for a few seconds and then died. Now neither speakers are making any sound. Both speakers crackle with the bias turned up. I forgot to mention this, but yesterday the left speaker died first and then the right speaker died too. So, yesterday I thought it was the amp. So, this afternoon I turned on the system again and only the right speaker worked, so I thought it wasn’t the amp but the left speaker. Now I am thinking that it may be the amplifier with unstable output transistor or something like that. What do you think?