I'd go with the morels and xd 600/6. Your voltage should be around 14-14.4 with the car on so it's a little more power than your calculating. Anyways you'll never turn up the volume enough to use all that power unless you want your ears to bleed.
2006 BMW 325i Titanium Silver
Mods- 19" AG M310's hypersilver, LCI xenons, drilled and slotted rotors, OEM rear spoiler, OEM exhaust tips, brushed black interior trim, Viper 5904 alarm + remote start
Audio upgrades- Alpine S920HD, JL XD600/6, Jehnert XE200, Morel Hybrid Ovation II, Audioque 2200D, 2 Alpine SWR 12d4's (forward facing sealed from trunk)