Many factors were definitely in play here, as many said, aging components, damaged cables or loose connections, luckily it was attended too almost immediately and rectified, because it could have been worse. It could have blown a fuse, even damage one of your channels. I like to add one factor, especially when you stated, you have moved your system to another location. An under powered outlet could also contribute to that, however, having said that, you would have experience dimming of light during high volume play back or even clipping of the amplifier. Typically, most electrical receptacles in rooms are on 15 amp or 20 amp circuits, which would be enough for most devices. But it is something to also pay attention too in diagnosing a situation like this in the future.