It is actually a good idea to try this in various locations, before you start cutting permanent holes in the walls. Contrary to what Mr Potato said, there will be a sound/performance difference, sealed or not, between placing a speaker within a wall, on a wall, or away from a wall a bit. Once the speakers are within the wall you will get better reinforcement and boundary effects that will aid in the bass frequencies. As Mark pointed out the speakers might sound a little thin for testing, but that is ok. In my testing of the new onwall m22's, before they were released, I experienced a very noticeable difference "on the wall" versus only 6" away from the wall. The inwall speakers should sound better once permanately mounted.
