id say no more then 18ft if your tucking the wire under door trim/carpet
Well a pretty known fact about audio stuff is that most amp kits that you buy usually have 17 feet of power wire in them. I personally dont like the amp kits, id rather just buy quality wire imo. I actually used 20 feet because i have a capacitor so i needed a little extra plus id rather get a little more incase something happens so 20 ft for me was perfect. RCA wires i would just get around 16 or 17 feet, these can be like a foot shorter becuase they travel less distance than power wire.