I tend to agree with you, that the more powerful woofers sound, well, more powerful. The Deltas have rising response into the midrange, like most other high efficiency wide range speakers. The Professional and Stage Series speakers don't have nearly this rising response and they also have a smoother response curve in the bottom octaves, because the Professional and Stage Series offerings are slightly overdamped.Each of these sound good without subs, but all can benefit by having them. It's always good to have more bass sound sources indoors, as it serves to smooth room modes in addition to adding LF extension.