Yes, you can place every kind of object on a different level.
There is no need of looking for workarounds, as I've stated before, for objects that aren't either on the floor or on the ceiling, the wiring will start from their backside, so if the backside is inside the wall, the wiring will be too.
If you want that the wiring connects two objects without passing through the floor, then the backside of these objects must lay on the same line (there is 1 cm tolerance).
Examples:
