As Trifid said it's peak power usually refferd to as PMPO,PMPO stands for "Peak Music Power Output" or "Peak Momentary Power Output". Notice the word peak. The vendor of the product calculates PMPO based on the maximum power output of the device under perfect conditions and 100% efficiency. These conditions are impossible to obtain, and no device can sustain the PMPO power for any significant length of time without being ruined. The PMPO power relies on the fact that amplifiers can provide short bursts (basically on the order of milliseconds) of very high power. Over time, these short bursts when averaged with the lower output powers, gives the real value.