That would depend on which way the ceiling joists run for the upstairs. If they are run in the same direction you need to go with the wire then you are ok as you could run the wire up to the ceiling and across to the next speaker but if they are perpendicular, you are looking at cutting into wall board, either on the ceiling or just the walls themselves and then drillling holes in the studs replacing wallboard, it gets very messy.
From the pics I think you might be out of luck, except for the messy part. You could paint the wires the same color as the wall and tack them in place very neatly to conceal them over to the next surround as an option. Latex paint is wonderful stuff, it sticks to almost anything.
