"Do high efficiency woofers need some power to overcome suspension stiffness and open them up?"I think so. From my trial and errors I've found rolled surrounds and loose suspensions, lower compliance, higher Vas, get punchy at lower levels. I think this is why some folks like Altecs vs. new pro-sound types. I've tried only 6 different 15s and found the woofer from the Pioneer CS99A and Cerwin Vega S2 to sound best at low levels, the EV DL15W has excellent bass but a little disconnected in the mids so likes lower crossover,