infinity amp issues

are his woofers ok? I would expect a bad voice coil. Thats the main cause of a protect light, OR possibly poor battery or ground connection to the amp.  I am not even sure an amp will go into protect from a broken rca end.

What does the front speaker outputs have to do with the subs?  I am assuming it is a pioneer avic310? It has an rca output, with subwoofer controls built in to the deck.  That should be what the sub amp is connected to. 

If you didnt see the magic blue smoke escape from the amp, disconnect the woofers and power up the amp. If it does not go into protect, check the subs one at a time.

i'll try and clarify myslef, the speakers are all good (tested them) the way the system was hooked up is the amp power'd the front speakers and the sub, the rear speakers were running off the deck alone.  once i had everything wired i turned the system on to set all the controls, within 5 seconds the amp is blown (smokes comming out, and the output terminals are sparking)  so i shut everything off and make sure everything was good. it was so i tried it once more (figureing what the heck can hurt, the amps already crippled) at this point the amp smoked again for a second then shut itself off completly. (i only had the rca cables connected, not eh speaker wires)  once that was done, they guy really wanted his bluetooth back so i thought i would connect his front speakers up to the deck (rather then running through the amp). and to which i had nothing on the front speaker wires from the deck.  the amp previouse amp was disconnected by myself and just disconnected, (fuses pulled etc) but nothing else had been changed.

The part where you say the output terminals were sparking concerns me!  Either the amp was bad, but you said it was new, so its not likley. or there IS a problem with the speakers or wires to the speakers.  Check all the wires that go from the amp to the front speakers individually to GROUND ( Each + and each -). They should NOT read anything. If they do, trace them out to find the short.  If you measure ohms betweem the pos and neg wires to the speakers, that WONT always show if one or the other is shorted to the body.

I think thats where your problem is, that may have burned out the front outputs at the deck too. Have you tried a test speaker connected directly to the front speaker output of the deck?  Make sure both left and right are disconnected from the car first.

My point is there might be a problem in the wires you havent detected.  Take a speaker and 1 foot of wire, connect it to the front out on the deck WITHOUT the wires connected anywhere else.  Pioneer uses One amp to run all four speakers, 90% of the time, if the amp is bad in the deck, it blows the decks fuse, or NO sound from any speakers.  The fact that the rears still work, tells me there is a 90% chance the front wires are grounding somewhere in the car.  Without testing each wire to ground, you do not know if they are ok or not.

You might try to "pop" them with a small battery, or test for 4 ohms across the wires, BUT that is not checking the wires completely!  If everything checks OK, you got a dud replacement amp. BUT that is VERY rare these days!