just make sure u solder the wire connections, don't want them corroding or pulling apart over time.. then heatshrink over the bare copper so they wont short out on another connection or earthing point.

And yes, the main power wire to the HU should have a 10amp fuse connected, 1 last point of safety between the 2 inline fuses already connected. Don't want to blow the HU or start a fire in the cabin