The power supply in your summits has a "signal sensing circuit" built into it which turns off power to the ESL panel after 6 minutes of no signal being detected. This is designed this way so when you shut down your system, the panels will power down by themselves, which prolongs the life of the panel. Unfortunately, at very low volume levels, the signal is not detected and the circuit shuts off power to the panel. For several minutes you will still continue to hear sound coming from the panel and then you will only hear the low frequencies coming from the sub and nothing coming from the panel. The blue lights on the back of the panel will turn off and there's an LED by the power cord that will turn amber. Turn the volume up and the speaker senses the circuit and powers up the panel and you're back in business.
I'm not sure what the crackling you heard was...
This has been discussed before.. Do a search for "signal sensing circuit" to learn more...
