How to Calculate the Best Wire Gauge for Your Car Amplifier Dual amp set up. I have a Kicker CX300.1 and KX400.4. If it maters CX300.1 with 2subs Kicker DC12, KX400.4 with 2 KSS650 and 2KSC650. What size amp fuse do I want to use? What size power and ground wire should I use? Distribution blocks on negative and positive or just positive or non? If distribution block what wire size before and after blocks.