I replaced the power amp and right side door speaker seems blown. All the other speakers seem fine. It is distorted / fuzzy bass. I am concerned it could also be the amp. How can I verify it is the speaker and not the amp before I get new door speakers?

I can switch with the left door speaker

 

That's what I'd do... switch the wires around at the amp and see if the other speaker sounds blown. Also, check to make sure you don't just have something loose on the door. my speaker grills one one side made noise after my son knocked them off (grrr, kids lol). Pretty easy fix, though