Can Membership allow access based solely on login without subscriptions?

I have a site which I need to lock from non-logged in users. It's a multisite installation and I am syncing users between sites using the "Multisite User Management" plugin at I simply need to create a visitor level that protects all content from non-logged-in members. Since the site does not use registrations with which to apply subscriptions, and I cannot define Membership access levels or subscriptions in the sync process, I really don't see how I can merely prevent non-logged-in access. I realize there are other solutions, plugins, auth_redirect(), etc, but I'd like to use Membership for some of its other features. Seems like a simple "User is logged in" in the access rules that you could drag to the positive rules of the visitor access level is what im looking for, unless there is something else I am overlooking?

Thanks in advance for any help.