i dont post much here but im getting ready to put a subwoofer in my 04 Mazda 3 sedan and i have a question. im gonna use a line output convertor that i bought up to an amp (not sure what one yet). im keeping the stock headunit thats why im using one. anyone here installed one of these convertors before and is there anything i need to watch out for? also, do i need to hook the wires up to the back of the stock headunit or can i tap into the wires on the rear door speakers? thanks. oh, i already got the subwoofer. picked up an MB Quart 10" dual voice coil subwoofer. the model number is DWH 254 that i picked up for $40 on sale at a local car audio shop. i didnt need anything hardcore, just want to add an extra kick to my music.