1/2″ line terminus make all the difference. With the SQ enclosure (right) the Hybrid Audio I6SW plays flat almost all the way on the volume control (50 max) without much hint of stress. With the SPL or SQL enclosure, the sub peaks somewhat and can only go to around 40-43 before it starts to get uncomfortable. However, at that point the mirrors are shaking and you can more than feel the sub through the seat. Impressive for what is in reality a 6.6″ sub, with only a 5.8″ cone! Small this sub might be, but it shouldn’t be overlooked.