parasound to a sub

has anyone had a problem hooking a parasound amp or pre to an earthquake sub?
blown 2 sets of tweeters, one in an old pair of bostons and now in a new pair of paradigms.
earthquake had both high level input and low thru Rca and recommended the Rca
used the normal out of the pre to the sub rca input and got a hum that eventually blew the tweeters.
Could it be cabling? or hook up
thanks in advance
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took a homemade monster cable 12 ga zip cord with rca ends out of the parasound pre from the normal output to the low level(recommended ) input of the sub. Then connected to the other out of the pre (the DC protected )to the power amp.
This sure seems to be it as i had the sub hooked up high level amp out to speaker in on the sub then out to the towers for months with no problem, it was only when i made the new cables and changed to hook up did i blow things up>
john m
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