Very disappointed to find my very lightly used CMT-340 blew a speaker for no apparent reason. :-(

I have really only used these speakers for TV/theater, but I recently had a small amp hooked up (50WPC !!) and was listening to CDs at medium vol when suddenly I noticed a buzzing sound coming from one of the speakers. I couldn't believe it as I have never blown a speaker before EVER, but when I took off the screen and checked, sure enough it was blown.

I think I am just out of warranty so will probably have to eat the cost. I just wonder if this is common with these speakers at just ordinary volume. They were factory seconds - I thought just for cosmetic reasons - but maybe that had something to do with it??