The ULS 15 is for when you want lots of output and high sound quality from a sub that can go into a lot more places because of the smaller size, higher WAF, and wireless connectivity (I use my ULS-15s as desktop speakers). You can get get more output from larger subs for roughly the same price. The output level can be roughly that of a VTF3, so it is not shy in loudness. It has other features such as a ULF Trim, XLR inputs, and a pretty serious XBL^2 driver, so it's a pretty deluxe sealed 15". If you want substantially better from a sealed 15", you have to move up quite a bit in price range, up to a Velodyne DD15 or Paradigm Sub 25. I think the continuous RMS power is somewhere between 500 and 600 watts, my guess is 550.