Wireworld Patinum Electra 7

Recently I purchased a used wireworldPatinum Electra 7.  The high is extremely high n mid is not as clear.  I suspect I might have purchased a counterfeit power cable!  Any idea? Usually how long does it take a used cable to settle in the system? I have about 10 hours on them, the seller purchased it back in 2012 n swapped the occ silver plug. Thanks