Hi, Recently I upgraded by 'old' SVS PC passive subs with SV's new NSD Woofer. I have owned two PC passive subs for around 8 years. This is the second woofer upgrade that SVS has offered. I've bought both. The original subs were good but good not handle the amount of bass I like [for movies]. For music they have always been great. The first upgrade improved on the .1 bass for films but still I could not play them as loud as I would have liked to. With the new NSD Woofer my PC's shake the house, literally. They are clear, concise, and accurate. During the scene in the new Blu-Ray version of Fantastic Four when the space station is hit by the solar storm it felt has if I was on the station. The frequencies below audio hearing range were well represented. These woofers will play louder than even I enjoy and they are not boomy at all. They do not seem to be straining as they shake my floor. Maybe I should turn down the gain. If you have an old SVS PC passive sub or two I highly recommend the new NSD Woofer.