Our new Honda has a 120 watt radio system. Not knowing much about audio systems, is this a good thing? Does wattage affect the quality of the sound, or does it give better reception?
Wattage is a power rating, more power means that the signal is stronger and can power more speakers/drive larger magnets resulting in more volume (louder). Wattage does not affect signal conditioning (reception) and has no direct effect on sound quality (other than a stronger signal may be less susceptible to background or ambient noise).
Sound systems may have two power rating: peak and average. Peak power can not be sustained, but is availble for a short period. Its importance is for deliverance of clean, sharp percussion and peak sound such as a hard struck piano note, clash of cymbols, and snare drum. Peak power can not be maintained for a long cadence on a snare drum. Here, average power is important. Peak power helps to put the punch into a booming base note, but it can not sustain it.