Vidiot33 ... High efficiency is a fascinating aspect of performance when it comes to subwoofers. The original Eminence driver we used in the Chase line of subs was spec'ed to about 95 dB / 1 watt / 1 meter. In the sealed box, by the time we got to 20 Hz, it was about 80 dB 1 watt / 1 meter, and in the larger vented box it was about 85 dB. I am going to guess that the new driver in the V-3601 is closer to 90 dB in the 1 watt / 1 meter range for specified sensitivity in a free space (think infinite baffle) configuration. The mass of the driver is likely higher than the older Eminence, and the result will be about the same sensitivity in the really deep bass at the cost of some sensitivity in the upper bass. Output will increase in the deepest bass, with a small possible loss in the upper bass, again in contrast to the older Eminence. The V-3601 strikes a really good balance between the performance of the older Eminence driver and drivers such as the TC Sounds LMS-5400. Mid bass slam is not lacking, but the "shudder effect" in the deepest bass is definitely improved over the Eminence drivers. What astounds me is how PSA got this extension in a relatively small cabinet for two drivers in a vented enclosure. This is especially notable considering it was not done by under porting the unit. The slot port is MASSIVE - with a cross section close to a single 8 inch round port. Chuffing never occurs. To answer your question ... I think this driver/enclosure/vent tuning/amp/DSP combo is very well thought out. A lot of work went into the design to get this level of performance. It's not really efficiency that is making the performance, it's solid engineering.