Need help with Kinergetics Subs - Newbie

Total newbie question here...

Denon 2805 receiver
Spica TC-50 mains
Kinergetics SW-200 subs
Jamo S3 surround

I have a pair of Kinergetics SW-200 subs that have a problem that I need help troubleshooting. If you're not familiar with these older subs, they are a left and right sub each with two 10" cone speakers. Since my Denon 2805 only has one sub pre-amp out, I split this signal and feed to the L/R channels on the Kinergetics amp.

The problem is when the bass gets to a moderate level, the right sub box (again with two 10" speakers in it) starts to make a loud jackhammering staticy type sound. One of those wrong sounds that makes you run to turn down the volume before your system blows up. Both of the speakers in the right box seem to break down at the same time, so I'm not sure if it the speaker cones / coils or something with the electronics in the box. I usually blow a fuse soon after, too.

I don't see any visible cone damage and the subs sound fine at lower volume levels.

The left speaker box will make the same sound but only at a much higher level. The right speaker box definitely has the problem long before the left does. Am I just pushing the subs too hard for home theatre? They seem to be made to be a very subtle sub.

Anyone familiar with Kinergetic Subs? Are they right for home theatre or am I just trying to do something they weren't made for? I always thought "a sub is a sub" and can be used for multiple applcations, but maybe these aren't cut out for HT.

Anyone have ideas of what the problem is?

Thanks for any ideas / help!

John