http://www.caraudio.com/forums/amplifier-classifieds/515147-mmats-hd4000-1-a.html
video of amp doing 3k at 2 ohm with only 2 4 guage inputs seen this do 5k at 1 ohm dual 100 amps, not going to be a 5k amp according to you. Also how do the old Orion amps only come with 30 amp fuses and put out 800 plus rms. I personally would get a mmats amp over sundown, audioque, crescendo etc. But they are just too expensive for my taste.
and 76 percent at full power is extremely efficient no cheap 4 ohm efficiency rating.
150v rails vs smaller 60v or 80v