What you are asking for doesn't really make sense. You need to AC adapter SOMEHERE to convert the 120 volt AC to proper voltage. I think its probably DC too, but I could be wrong.
I would believe that the other units mentioned also have AC adapters- they are just integrated into the unit so you don't see them.
Its really not the end of the world either way. If you dont want the enclosure, take the line you have a put in an all weather outlet and then plug the AC adaptor into it.