A coworker of mine has an Ample A1100DX that I gave him a while back. It's worked fine at 2ohms until recently. He said the volume just got lower and lower until there was no sound at all. He checked his subs and the voice coils were both open. So we swapped them for a pair of Vegas that I had reconed. Now it's running at 4ohms and all was good when we first powered it. But after a day or two, the volume begain decreasing again. He shut it down to avoid killing more speakers. Has anyone run into this? It has me baffled... Please help?