wiring after market speakers to an amp.

[Domosofly]

Which way is the best way to wire after-market speakers to an amplifier.
Should I run speaker wires to the the speakers them selves and through the door directly to the amp, or run wire from the radio wiring harness to the amp?

Also i'm using the factory speaker adapters to mount my speakers would this be a problem later in the future? They are screwed into the adapter , I just feel they aren't really secure; will the vibrations from the music loosen the screws and eventually force them to fall out?

Thanks for any help.