Have you tried setting a session variable when someone log in to be set to the user level column in your database?
For example, you could set a session variable named "userlevel" that gets it's info from the user level column. Let's pretend in my case, I login and I am an admin.
So, you could trigger based on that checking if $_SESSION['userlevel'] is equal to admin then use pluginA. If $_SESSION['userlevel] is equal to user, than use pluginB, etc.