Hifonics brx1600.1d or audio technix 800.1 with sundown e15s?

hi im getting 2 sundown e15s (rated veryyyy conservatively at 400 watts each) and im stuck between two amps. the first is a hifonics brx1600.1. if i do that, i wont do any electrical upgrades so it doesnt put out the full 1600, just to keep the subs from clipping and what not. the second amp is an audio technix at800.1d. its rated 800 watts at 12 volts (976 at 13.5), and also has a clipping detector on the gain remote. just really stuck between the two because the at800.1 will cost the same as the 1600 after a big 3 upgrade. how many watts would the 1600 do at 13.5 volts with no upgrades? thanks a lottt