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To start, I have 2 15's and a 3000 watt amp. The amp settings have been the same for a few months. I never turn the volume up past 29/40. (stock components start to distort) They have sounded great up until tonight when I got off work and was giving a demo. When I opened the trunk my subs were giving off this really bad distortion, almost as if they were blown. They still hit just as hard but I still get the distortion even at lower volumes. . . Any idea what it could be??