While the Sunfire amps are very efficient overall, they still need an unrestricted view of the outlet to work best. The DBX is not nearly as efficient and will always want to pull measurably more juice for the same volume level.
Since anything that limits current for an amp is a BAD thing, you would really need some way to filter but not constrict current flow to each of the three amps ( if i understood your description right ). The only way to do this would be to have a PLC that could EASILY pass 45 amps continuously.
In order for the standard Sunfire to meet spec all the way down to 2 ohms, it needs 20 amps by itself. Then again, i sincerely doubt that you would be able to make use of 2400 watts rms on a sustained basis and retain your hearing. That is, unless you had very low efficiency speakers and a large room. The fact that you have TWO Sunfire's driving the mains would REALLY make the electric meter spin if trying to "raise the roof" at low impedances.
If you have all of these amps plugged into the same circuit, a high current PLC is not that big of a deal though. The amps are already getting choked if you have inefficient speakers and tend to stand on the throttle. Then again, adding even more restriction into something that is already "bottlenecked" may be the straw that breaks the camels back. Sean