Memphis mclass subs

About 4 days ago i tried powering my back speakers by a 2 channel amp and when i would turn the car on the speakers would have a very loud frequency sound coming out of the speakers and when i would turn the volume all the way down the noise would still occur. On top of that the subs would have a low sounding bursts of hits. I checked the polarity on the door speakers and the amp, also checked all the fuses. So I rewired the back speakers to the back of the HU and they worked fine. But on the other hand the subs wouldnt work when the system was back to normal. I took out the box and took out the subs and checked the ohms on each speaker and both speakers read 0 ohms(short circuted.) All 4 coils(2 per speaker) failed this way. Both, the 2 channel amp for the speakers and the mono JBL amp for the subs, are hooked up to a capacitor and both amps are also running off one rca cable coming from the back of the HU and are split into 2 cables with Y splitter cables. I need to know what happened and what can i do to prevent this from happening again. I have the reciept where i bought them at the local memphis dealer about 20 minutes away, the subs also have a full life time warranty. Are the subs fixable or do they need to be totally replaced?03 F150 on 24's

HU:Pioneer DVD5700

Frt:MC57

Subs:(12)S12L7

Amps:(3)KX2500.1's, MC-2004

Sounds like a mess. You should drive to your dealer and have them help you. I could start guessing, but I have no experience with caps as I've never heard one good reason to buy one. (I'm really only responding to /bump this :-) - hope someone can help.)New Project: 2003 Pathfinder

I went to the memphis dealer today and he said he would send the subs to memphis and have them fix them and then have them send it back all for $40(shipping both ways). Sounds like a deal to me, so i left the subs at the shop. Hes gonna special order all the components, speakers and amp from memphis and do a professional install for me and set all my gains. Im pretty happy i can finally turn up my system to where i cant even take it and its not distorting. If anyone else knows what the problem was or even has an idea then just post it please. Thankyou03 F150 on 24's

HU:Pioneer DVD5700

Frt:MC57

Subs:(12)S12L7

Amps:(3)KX2500.1's, MC-2004