is there a problem with impedance when splicing in a line out put converter? in other words i still want the four speakers to play thru the stock head unit and the line out put converter to run to the amp for the subs, has anybody done this and had any problems with the stock head unit? is there any other way it can be done? i did a search on the net and found nothing that helped me. i would like to add a amp and sub woofer as cheap as possible and still have the stock head unit play 4 speakers. i hope i can splice in to the stock wires.