HoustinoJillian
name's JUSTIN
the website i'm looking at (cardomain.com) reccomends buying this to use in addition to the wiring harness adapter. i will be using a pioneer head unit with 50x4 watt output (this one ) do i need this to hook up to my factory speakers (say "premium sound" on the speaker grilles)? and if not necessary, will it be better to have when i upgrade the speakers later on? basically i dont know what this thing is, and i want to make sure cardomain's not just trying to sell an extra 20 bucks, thanks.... and btw, anyone got a coupon code i could use? 