punch hx2 blown! what subs now?

The reason your sub would not move is because it the wreckless power thrown on it was not enough clean power to move it correctly, thus merely generating heat and physically melting the voice coil and welding it in place, locking the sub as you stated.  And I meant no offense by that, it's just how these things work. 

Adire Audio is a very reputable company with great products at great prices.  I used two tempest 15"s in a sealed box in the trunk of a honda accord a few years back when all they offered was the shiva, tempest, and maelstrom as home audio subs, and squeezed out a legal 153.7dB on an AudioControl meter.  They were powered with a JBL 1200watt rms amp and ran just fine for as long as I tortured them.  That was entertaining to say the least to watch this $450 setup blow away many other extremely expensive setups.  My only complaint was the awful sound quality at these brutal levels, but that was soon remedied by a tahoe who wanted a close-up view of my head unit.  

http://www.adireaudio.com/

These subs are rated to handle 500rms according the RF's owner's manual.  If you are putting 350 rms to the sub and they blew it sounds like a distortion problem. 

There are many reasons why a sub would stop playing.  You can over push a sub and cause the voice coil to freeze or break or your can feed a sub a lot of distortion and ruin it. 

AFAccord, distortion is not the only thing that can kill a sub.  Pushing more than the recommend RMS to a sub of a long period of time can also cause it the stop working.  Subs use air to keep cool like a car uses water, oil and air to stay cool.  If the air that the sub breeds is hotter than what the speaker can withstand and the sub is being demanded to go beyond it's true ratings and some point and time the sub will fail. 

I vote for the shivas as well.  Wire them in Parallel Parallel Parallel.  Making a 2ohm connection. I bet you will notice that they hit harder then the kickers.  Since the Xmax on them is prolly double.lol

Audiobahn!  dare you to say that here.  Audiobahn is the S#$T of the world.  You stay far far away from their "products"

If you go with the shivas, i say scrap the proted box and go with a sealed box.  You could make one easy, and it shouldnt have any of the problems you are facing.  that is if the subs weren't getting a clipped signal and the simply fried.

ok since i cant use the shiva subs...ANY other options thats got a good bang for the buck ratio?

i could run a single L7 15"?