A:AnswerWhich sub?? Typically a subwoofer requires more power to play than a set of full range speakers so an amplifier is needed. It isn't necessary that you have an amplifier but you can purchase one at time of installation. The auto tech can help you with that process.
A:AnswerI would contact your local Geek Squad installer ... it is a guaranteed good job! I used to do all of this type of work myself but the value and quality of work makes it so that I just let my local guy do it! Good luck!