Two-Amplifier System - Front + Subwoofer

This is the common "front stage plus sub" layout: one amp for the cabin speakers, one amp for the subwoofer, and one clean main power path split at a distribution block.

Two-amplifier system diagram showing source, fused distribution, front amp, sub amp, front speakers, subwoofer, signal paths, power, and grounds. — Two-Amplifier System - Front + Subwoofer

Fast Rules

Fuse the main feed at the battery and protect each branch after the distribution block.
Use one clean star ground strategy instead of random chassis points.
Keep the sub signal path clean and separate from power wiring.
Check amplifier current needs before assuming one main cable is still big enough.