how should I wire 2 Rockford fosgate p312d4 with a Sony xm-d9001gtr amplifier?

[Ethan]

that will add the most bass

[Karl]

that amp is only 2 ohm stable, so if you want both dual 4 ohms subs hooked up you can doing a 1 or 4 ohm load, but you cant do a 1 since your amp doesnt do 1 ohm. the most you will get out on that amp is 550 watts at 4 ohm, 550 is enough watts to power one of those subs, you will be underpowering it significantly.