wiring for solenoids and amplifiers?

What's up, I sort of have a wiring dilemma on my hands. I currently have an 800:1 Phoenix Gold AMP running on fused 4gauge wire & 2 AutoLoc 35-lb pull solenoids to pop the front doors running on separate 8gauge fused wiring wiring. The power wires to the solenoids are fused at 30 each. I have plans of adding another AMP (400 watt range) to power my front and rears. Rather than running 4 separate power wires, I'd like to run one thick wire off the battery, fuse it then into a distribution block. My problem is I have no idea how thick of a wire the main line should be and how big of a fuse should be on it.