I have an Alpine amp MRP-M500, and I had a 12" Rockford Fosgate P1S2-12 subwoofer until I blew it the other day. I would like to replace it with another 12" Rockford sub, and I found the same one on Amazon for a fairly cheaper price, but I have the option of getting it in a 2 Ohm or a 4 Ohm...