@ricred1, I am only referring to two subwoofers in the ML line, the Balanced Force series. The others are no better than anyone else. There are absolutes is audio. In this case a subwoofer with two opposing drivers is going to perform better than a single driver sub of the same overall quality. Personally, I will not have any of them. I overbuild by own.
@12many , Yes! Isn't that something. Most woofers are actually lower midrange drivers. They are in a portion of the frequency range where we are very sensitive to pitch and distortion. Doppler distortion or Doppler pitch changes occur with objects in motion. The lower a woofer goes the further it has to move to project that frequency at similar volume. The motion becomes visible below about 100 Hz at a moderate volume. The smaller the woofer the more obvious it becomes unless it is used in multiples. The cone is travelling towards you then away from you, changing directions. The same thing occurs when a car passes you. If the driver leans on the horn while it is passing you the tone of the horn changes rather dramatically. Most of us have experienced this first hand. If not I am sure there are YouTubes that demonstrate this. In the case of the woofer, when it changes direction it is changing the pitch of every other note it carries. The larger the portion of the frequency range the woofer carries the more damage it does. In your case you are better off than the OP whose woofer covers another entire octave. Other than making more low end this is the other major reason to use a subwoofer. People will mention how much a subwoofer improves frequencies above the subwoofer range and this is why. What kills me is that most subwoofers do not include a high pass filter for the main speakers totally ignoring a major reason to use a subwoofer in the first place.
Please, if you are going to use subwoofer use a complete two way crossover. If you really want to take it to the next level use a digital crossover with bass management and room control which requires a measurement microphone usually supplied with the crossover. Some of the very expensive units do not supply a microphone. They expect the dealer to install and adjust the crossover. They will sell you the microphone and computer program as an option. This is a very powerful system. If you think you can do it by ear, have fun trying. I tried for 20 years and could never get it to my satisfaction until I got a TacT 2.2X. It did it in about 1 hour and the bulk of that time was me trying to figure out how it worked. The manual sucked.