It's not like he is using the actual in wall speaker outside of the wall, it's a sealed speaker. Of course it may sound slightly different than if it is installed in a wall with the way sound will react off the wall, I should have worded that differently. If you really want to get into it you could say the speakers are not going to sound the same in spare drywall and in a different room, than they will finally installed in a normal wall with drywall/studs in your destined room for them.