Thanks for that I will be checking that next. I suspected this.

Looking for help to understand this problem a little more and what I should be testing for. Crown XLS2002 in bridged powering a Dayton dual voice coil UM18-22 18 inch driver in series at 4 ohms in a custom enclosure. Setup ran well for about 2 weeks then it didn't. The first driver when tested after the failure one coil was at 24 ohms and the other coil at 10 ohms but cone movement is smooth. Got 2nd driver and installed, it cooked right away. Coils ohm at 2 ohms each but the cone sounds crunchy. We believe that unfortunately it is the amp that caused this but I'm looking for advice on what I...