can I leave my original stereo on?

I have a 2006 3500 doge and my back door speakers are out so I’m thinking of switching them all out for some alpines nothing crazy I think the factory speakers are loud enough for me but I would like to keep the stereo original if possible. And for those who don’t have Bluetooth on their stereos what do yall recommend is better aux cord or a Bluetooth device that plugs in the charger port ? Any help appreciated thanks