It seems to me that AO can be a solution, but sometimes it's a matter of the right unit settings, some tutorials are made with inch-settings. When you're using mm or cm.settings you have to multiply your A0 settings by 25.4 or 2.54 to get the right results  (25 or 2.5 will be right also). When you use AO in your materials, you don't have to use it in your lights.

best regards,

Bopperthijs

-How can you improve things when you don't make mistakes?