Actually the Federal Trade Commission stepped in and set standards in the 1970s because of wild "peak power" claims by amp manufacturers. The standard was supposed to be both channels driven to a stated distortion level into a stated load and measured under continous conditions across the audio band. This was to be measured after a preconditioning period at 1/3rd power for one hour which is the point of maximum heating for solid state amplifiers. Most amplifier manufacturers complied and stated "100 watts continous (RMS), both channels driven into 8 ohms with no more than .01% distortion from 20Hz to 20kHz".

Obviously with the advent of home theater, some manufacturers (not Outlaw! ) have started to be real scumbags and rate their amplifiers dishonestly. It's probably time for the Federal Trade Commission to step in again and reign in these low lifes and force them to comply.