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
You'll have to be more specific on how the sub and electronics were/are cabled.
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
John, I don't see anything wrong with wiring the sub in parallel with the main speakers. People do it all the time. However, I've never heard of anyone using speaker cable as a line level interconnect. Usually, line level subwoofer cable is coax and shielded; that would take care of the hum. I don't see how that hum would have any effect on the main speakers, though.

Did you use the speaker cable as an interconnect from the preamp to the amp? If so, I'm guessing that is where the problem exists. Not the cable itself, but probably the connections.

You can buy very good interconnect cables at very reasonable prices from Blue Jeans Cable. For RCA connections, I use the Belden 1505F coax.