I have 4 ga power wire ( Kicker amp wire ) running to an MTX 64w X 4 c amp and a Bazooka sub amp at @ 220w. Both amps accept 4 ga input but my distribution blocks are 4ga input with two 8 ga outputs. Will these amps still perfrom as well with 8 ga inputs (@ 8" long 8 ga ) as they would with 4 ga inputs? Also, should I individually ground each amp or send 8 ga from each to a distribution block and ground from the block with 4 ga?

 

As long as your distrubition block is within a few feet of your amps, running 8 guage to your amps from a main 4 guage feed is fine. There is a mathmatical equation for it but you have very small amps that arent going to pull much current so it isnt worth researching.

 

Thanks for the input. So it sounds like I'll be OK with 8 ga. Just wondering though, at what point (RMS watts) would it be neccessary to use 4 ga input to the amps? Also, does this apply to the ground as well?

 

8 AWG is good for about 50A (running the length of your truck) and 4 AWG about 100A.

50A = 350 watts RMS
100A = 700 watts RMS

Always ground your amps with the same gauge wire that's supplying the power, and ground as close to the amp as possible. Rinning 8 AWG grounds to a distro block and then grounding the distro block with 4 AWG is fine, but try to keep the total length under 3 feet.

Your main should be fused at around 70A, and each of the 8 AWG feeds should be fused at 40A.