The Hsus are not underpowered. A high sensitivity driver and large cabinet mean they don't need a lot of juice to get loud. Pay attention to those measurements, the Hsu's have more output, less distortion, greater linearity, better long-term output, and less compression than the XV15s, all the while with less amplification. The VTF15h is a great illustration of why wattage do not matter, only end performance does.