take it from someone who has 2 pb 3000d's,
if you cant keep your voltage above a 12.6 dont strap these amps they dont have a low voltage protector and they blow out. if you have them strapped your master amp blows.
i heard the new pbx's dont handle as much power as the old ones and the 4000d's are still made like the old ones so i think they should have plenty of power