This is scary man. There's no way you can run your amp off this power. You need to run 4 gauge from your battery and amp. The wires powering the fuse panel are probably smaller than the wire going to your amp now. Think of this like trying to use a fire hose thats connected to your garden hose. A 750watt amp needs alot more current than a 75watt amp. Your current wire size and supply is not enough to supply your amp with the needed current.