I'm thinking your volume is turned up somewhat loud. If so, the alarm on the Adcom 545 is an indication that you have reached the maximum output for the amp. The popping sound is probably the woofer in that speaker bottoming out. I'm sure if you turn it down slightly, this will not happen. You may need a larger amp, if the speaker can handle the extra power, or a speaker with higher sensitivity to get more volume using the Adcom amp.