Thank goodness Amberwolf was on this thread.
Balancing channels stopped mattering after the days of tubes and output transformers.
The right side of that modern chip amps has no idea if the left side is on the same planet with it or not, let alone if it's connected to a speaker.
Your popping sound is from the step-wave function of connecting or disconnecting an input source, you can fix it by adding a resistor typically if you care, but it's not going to be related to over-powering your speaker or putting excessive heat into the voice coils of the drivers.
The amp only puts as much power into the speakers as you request of it by turning up the volume knob, and it's always better to have more amp than speaker for sound quality reasons if it's something you care about, but either way with any amp, just turning it down until the speaker isn't mechanically clipping or overheating it's voice coil is the solution (or throw the voice coil pair in series if for some reason you can't control yourself on the volume knob after it starts sounding awful).
