In a nutshell max power is the power that a piece of equipment can cope with for a very brief period of time. RMS (Root Mean Squared) is the continuous sustainable output from the device (or input in the case of a speaker). RMS is the only rating worth reading in the way of power handling. The max power can be a fantasy figure and means next to nothing. Max power is often reffered to by shady companies as PMPO (Peak Music Power Output) and is just there to fool you into thinking it is the acronym that you should be reading (RMS).
so if those sony Xplods say they can handle 1200 max watts continuous and 350 RMS what does this mean?
If you are going to listen to them for a long period of time you should only have 350 watt's to them. If you put 1200 to the sub it would cause som dammage more than likely.. The rms means how much it can handle constantly.