I have one JL audio 250 mono amp on one JL 15w04 sub and it is doing some weird stuff. This is my second JL amp in about two weeks, I thought I blew the first one. Everything was fine, I lost bass to the sub and just got a flutterign out of the sub. It seemed like a 15Hz bass note even when the volume was turned all the way down. Now the amp power light is on, but no sound. This is exactly what happened to the first amp. Any ideas?