HU adaptor?

I am building a system and need some help. I will be replacing the HU and using external amps. Do I need to have a full wiring adaptor or can I just hook up the power and antenna wires?

You can just tap in. I personally still reccomend a harness. Makes life a billion times easier.. Especially when going back to stock for what ever reason...

12vc = orange
12vs = yellow
ground = black
power antenna = pink

Thanks.