Fred, dynamic power is a valid method of measuring amplifier output suggested by the IHF. It's measured by applying a tone burst for 20 milliseconds on and 480 milliseconds off every half second. The idea is that 20 milliseconds roughly corresponds to the length of a musical peak on a instrument, following which the sound level falls off. This tends to give a number about 20-30% higher than the continuous power rating which the FTC regulations require for amplifiers advertised in the U.S. The basic FTC requirement is at least two channels driven simultaneously at the full rated power for at least five minutes continuously.
