Chris, on power consumption figures there's no specific standard required by law for stating them. In contrast, for power output, FTC regulations set a required standard which we can rely on.
The first point is that the consumption number isn't at maximum power unless explicit language such as "maximum" or "full power" is used, which few do. Usually it's at some average power output, such as the 1/8th power which Underwriters Laboratory uses in testing for overheating since 1/8th is considered to be roughly the average usage in playing an entire disc. So, a number such as 400 watts for consumption in a 7x100 watt unit isn't inconsistent(and certainly not lying, as some of those lacking knowledge of the measurement basis claim)since it's typically measured using about 90 watts(1/8th)rather than 700 watts and class AB amplifier efficiency is on the order of 20% at 1/8th power(compared to around 50% at full power). Therefore 400 watts or so input is required for about 90 watts output.
The reason that when the consumption number is given in amperes rather than watts it seems to give a considerably different result is that although a watt is defined basically as a volt x an ampere, in actual audio amplifier circuitry the voltage and current aren't perfectly in phase with each other and the result of volts times amps is substantially fewer watts of power(typically around 70%). So the two units you mention would have about the same consumption when measured at the same output and both being stated in watts(or both in amperes).
