blowing fuses while setting gain?

specs: 2001 Honda Accord Kenwood 22RMS head unit 4 polk db651's powered by head unit 12"Alpine type x wired in parallel --> 2OHM load Alpine MRD-M1000, 1000RMS @ 2OHM problem: After installing everything correctly I put in a 50hz sine wave disc I made. I start to turn up the head unit with bass all the way down, get to 35 (max volume) and there is no audible distortion so I shrug it off and move to the sub. I start to turn the gain up from the minimum setting, the sub increasingly gets louder.. keep going until the knob is in the middle.. sub still increasing, no audible distortion. Keep going.. turn the knob a little past half way (0.5volts), and the sub shuts off... okay at this point I am scared that I melted a voice coil or something.. But that makes no sense, because a PDX1.1000 can fully power the type x without overpowering it, and this amp is rated for 1000RMS, so its probably under that. I go and check the fuse, what do you know the 80amp? glass AGU fuse is blown... Im running 2 gauge wire to the amp, with a 2 gauge ground tightened to the chassis of the car, with exposed metal. I just want to set the gain properly, I know this sub can handle more, whats blowing the fuse? (It was hot to the touch when I took it out. sorry for the long post, I tried to be as specific as I could, I am an amateur, so any suggestions welcome. thanks.

Doesn't that amp have (3) 30 amp fuses?  

i am an idiot wrote: Doesn't that amp have (3) 30 amp fuses?

OHHH SORRY, I didnt specify that the 80 amp glass fuse was on the 2 gauge wire in the engine compartment, thats what is blowing, not the amp!! sorry, oh and another correction, I ment 0.5 volts instead of 0.3 if that matters. so am I setting the gain wrong or what?

If the amp has 90 amps worth of fusing, and you have a 2 Ga. wire, don't you think you could use a bit more than 80 amps worth of fuse in the supply wire?

Not to mention the fact that an 80A fuse will only power an amplifier (even a Class D, and with the engine running, which you didn't specify, so I will assume engine off) to 850W out, at a theoretical MAXIMUM. Probably closer to 600 with engine off - certainly within the "safe" range of that woofer - which might explain why you heard no "complaining", before the fuse blew. (Class A/B numbers will be lower, even.) Your power wire needs to be LARGER than the total draw ever expected (in this case 90A - safely carried by a #8 @ 100A) but it isn't necessary to oversize like you did. Once the wire size is chosen, THEN you select a fuse that will provide protection for the car and the wire, while still allowing for adequate current for the accessories attached. The underhood fuse is NOT there to protect the amplifier - EVER (in my opinion - others will provide examples of amplifiers provided without fuses in their ends, but in those cases you add a protective fuse AT THE AMP - not under the hood). Had you chosen the #8, you would put a 100A fuse under the hood. A #4, 150A, and a #2, you can safely fuse all the way up at 225AIt all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."