one thing i would like to point out, is if the 2 amps have different regulation. for instance, if you have 2 1k amps, and a little 60a alternator, the power supply regulation may react differently, actually giving you more, or less power, which still jives with a watt is a watt. then, again, there is other factors, such as the procesing, dampening, and typical rail sag. i can say that i notice by ear that some cheaper amps, boasting astronomically high peak numbers sometimes have a "bubbly" sound to them, where as other amps, with peak numbers not much (less than half as much) more peak than rms can have a more solid sound.