My Infinity BU-120 sub-woofer is dead.  The amplifier S53AMI blew and from what I have been able to learn on the web this is not an uncommon problem.  Infinity can't help me since the company that manufactures the S53AMI is no longer in business.  I hope Infinity has learned a good lesson but I'm not going to buy from them or their parent company Harmon Kardon to find out.