Tex-ArozziThis sounds suspicious... if 400 W is the max power, then what is 200 W? Minimum??
All power measurements should be RMS.
Perhaps the higher one is only sustainable for a short time?
@JesseArt I'd use the lower one for comparing to other subs' ratings.
TigermanWatt ratings are a touchy subject with speakers. Manufacturers for years used different standards to advertise the highest number they could. RMS is emerging as the new standard, but not all manufacturers are playing along. You are correct that rms is the number to use to compare with other speakers. BUT, the higher number (known as "peak") is still important because your amp needs to be able to handle that power. When multiple speakers are attached to an amp, you want an amp that can handle the combined peak of all connected speakers.