samsung84: Well if it's your Amp you might want to contact Sim and hopefully you have a Warr. with that unit... I had a used Amp I bought from a local store they gave me 30 day warr. with it I always have a inexpensive (Cheap) pair of speakers around for testing, sure enough after about 3 hours of use the unit popped and smoked and blew out my tweeter on my Paradigm Mini Speakers. But the "A" holes at the store said they would not warr, the unit nor the speaker, lucky for me my other dealer got it repaired at no cost, I have never stepped foot back in the other store as their customer service blows! They gave me a $100 credit for a unit I paid $400 for.... Hence, anything I buy used, I use for about a month with the inexpensive speakers (Pioneers speakers) now then I hook them up too the big boys (C2's).. I highly recommended this when buying any Int. Amp or Amp used......