The 80W music is the much hated PMPO rating (Peak Music Power Output) and the other measurement is RMS (Root Mean Square) The PMPO is meant to be the maximum 'music power' of the speaker, which is rubbish, as the speaker would not last very long if it were run on that. It is also a marketing con, as the higher the figure you put on a speaker, the more attractive it becomes. RMS, is the true voltage power rating of the speaker in real terms. Much like an electric heater would have printed on it. Always go on the lower one of the two to get your speaker rating (RMS)