Hello everyone, I am new to this and I am sure this has been asked before. But I seem to be going round in circles. I am soon to have a convertible and have been looking to upgrade the sound system. I am not looking at changing the head unit as a facia seems to be difficult to get. It is the 7 speaker system but was wondering if the wiring is already in place to add 6x9 behind the seats? Do i have to run them from the amp or the door speakers? If i add a sub do I have the complicated wiring up to amp1 or again can it run from existing amp or from the door speaker wires. Thanks for any help just seems a bit tricky for something that should be easy to do.