Pro subs are generally about getting loud efficiently at 30hz and above. The Pro 5100 is a little different in that it will also get low but not as low as the LMS Ultra. The Pro 5100 has the edge at about 40hz and above over the LMS Ultra which is more meant to dig down deep in the nether regions of bass. I did hear what the Pro 5100 is based on, the Aura 1808, in the Wilson XS sub which used 2 1808's and was ported in a huge cabinet tuned to about 15 or 18hz. It was at a High Fi show and they used 2 of them driven by the biggest Krell mono blocks I have ever seen. Talk about bass that went right threw you, pretty much started my bass obsession right after that demo.