What happened here?

[sjohnso]

I am using a Denon AVR-95 to Klipsh Quintet 2.0s as mains and a Polk Audio CS 100 center channel speaker with two cheap RCAs for surround sound.
Recently, (I don't quite know when it happened) All three front speakers will only produce high frequency sounds from the tweeters. The woofers are completely dead.
I opened the speakers to see if the crossovers were damaged, but there are visible signs of damage. I connected the speaker directly to an audio source and there is sound ! ! !.
What couls have happened? How can I fix it?
Any help will be appreciated.

[Fantastic]

This sounds strange and looks like the woofer coils are burnt due to DC. But you say the speaker works normally with another amp.
That would indicate a problem with the Denon amp. First check the DC fuses inside the amp. There should be one for each rail.
But if there was DC on the output , there should have been some protection ( a relay usually ). Anyway check the fuses and the DC supply rail voltages.
Have you played it in normal stereo mode?

[sjohnso]

Fantastic, thanks for the reply. The Denon amp is actually doing fine. I have other speakers hooked up to it and they are working very well.
O clarify, I removed the woofers that were in damaged Klipsh and Polk speakers and jut connected the speaker wire from the denon amp and turned the volume up very slowly and alas, the woofers work fine. So it seems that something has happened in the crossover system.
I hope this sheds more light on the situation. Thanks.

[Bull]

As you said it might be the crossover.
If the tweeters work fine,and you've tested the bass drivers ou of the box.

Then it's either the internal wire or crossover or both.

Desolder or cut out the internal wire and test it with a multimeter.
If the wires ok,fine.

If not,buy some 12 gauge or 14 gauge high current ofc speaker cable,because thin cable sounds crap and cannot handle high power.

If it's the crossover,maybe just the solder connections have come loose.If they have just re-solder the wires to the crossover.
If the Inductor on the crossover for the bass[low pass] has fried,de solder and keep the old one.Take the burnt inductor to an electronic parts store and try to find the same one[same uh[micro henrys]and same voltage.It would be better to find a higher voltage and better quality inductor than the original,so that it would be harder to burn out.

If it's the copper tracks on the Printed circuit board,that are damaged,then you need an entire new 2 way crossover.

Hope this helps.