Sidebar: back in 1986 I purchased a passive 15 inch JBL B380 subwoofer. I powered it with a Sony 55es power amp which produced about 300 watts mono when bridged. This was not enough amplification as evidenced by clipping which made the speaker sound like a sledge hammer hitting a steel pylon. My need for more amp power was obvious so I replaced the 55es with an 80es which delivered about 560 watts to the speaker, solving the clipping problem. Later, reading the JBL manual, I discovered JBL recommended the speaker by powered by a 600 watt amp. The moral of this story is read your speaker manual to determine the speaker's amplification needs.