The system should have been off when you connected the cable. Then slowly introduce volume. If the cable is bad you won't be able to get any recourse since the problem may have happened after it was shipped or given to you. Are you sure they were both properly seated into the power amp? Why kind of cable with what kind of RCA connector on it? It would take the positive side only with neither the left or right ground present for this to happen unless you have monoblocks or dual mono design without common ground between the left and right channel. Sorry the tweeter was roasted. Good luck.
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