I have the SVS PB12/2 NSD and it is an awesome sub, far more than I needed (but got a great deal on B-Stock. ) The sub produces alot of tactile bass and fills my room with powerful deep, clean bass. Your gonna think when you get it that someting is wrong, because your used to hearing that "whoosh" sound which is distortion. With SVS you don't hear any distortion but you sure can feel the deep bass.
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BTW I have my gain set at only 2.5 and it produces this type of effect.
Here's a pic of mine, but mine is the dual 12's so yours will be just a tad smaller, but gives you an idea of the size your looking at.