I will disagree with the rest of you. As long as he is the owner or the owner doesn't mind a few rather large holes in the wall AND the common wall is insulated I think he would be all right to use the W series. I believe most of the sound is produced to go forward and would not resonate back through the wall much.
Ever stand behind your speakers? Not much happening back there when they are playing. I think as long as the crossover is relatively high, say 100hz the bass notes wouldn't be too bad going through the wall.
