Power gives some idea, but it is pretty much useless specification without knowing how it was measured. My amp, for instance, has module rated at 200W/4ohm but only 55W according to FTC measurement (that requires 1 hour preheat). It is possible for the lower continuous power amp to be actually louder. Music power delivered to speakers is only a few percent of peak power (unless anybody listens to sinewaves). What about distortions? Bel Canto makes the same amp as Rowland 102 (same B&O module) with 300W rating since they specify it at 10% distortions. In addition overdriving some amps is painful (odd harmonics) while other amps (including mine) have soft clipping. There is also not that much difference when power doubles (only 22% of perceived loudness). Perhaps it would be better to know peak power and max current but most often it is not available.
