your goona want to run that remote wire from your head unit, (I usually use blue)
run that into a coil side of a relay, or 4, or 10, use a relay for each item you are planning to turn on with the radio.
ex. neons, 2 fans, 2 amps, electronic cross over would require 6 relays.
some people may disagree on my use of a relay for each item, but if a relay goes bad (which does happen) then it sure would be nice to only loose 1 item right?
ill make you a schematic, but im doing it in paint, and quicly so all u other 12v gurus try not to beat me up to bad on it. lol
EDIT, #30 from the relay will be a 12volt positive source, so id use red to describe it as such to others who may be in there working, so all ud need to do is ground the ground wire from the fan, and connect #30 to the positive side of the fan
86 Should be grounded not have 12V on(will not trigger with +12 going to both sides of coil), Nice diagram though will print it out for the messups i work with…