Morse -
You didn't mention if you are running this amp on a base or in a mobile, but in either case it appears that you are not getting enough amperage to the amp for full output power. If the amp was 100% efficient (it isn't), it would require 50 amps @ 14 vdc to produce 700 watts. As ASW said, at the minimum you will need to upgrade the amp's power leads to #8 or larger, and eliminate any potential voltage drops (like the fuse holders). The best way to tell where you stand as far as your supply goes is to monitor the amp supply voltage with an analog meter, and see how much voltage drop you have when you keyup. First, check this voltage at the source ( where the amp's power leads are connected to the power supply. When you keyup, if you see more than a 1 vdc drop, you need to upgrade the supply. Then check the voltage inside the amp where the supply leads connect to the board. When you keyup, there should not be any additional drop over what you saw at the other end of the supply leads. If there is, then the supply leads are too small and need to be upgraded.
- J.J.