This past weekend a friend and I spent an afternoon listening comparatively to a collection of powered audio monitors. It was by no means a scientific study, just a casual session of listing to music in a focused manner.
We used three Slim Devices Squeezebox 3s as sources, all playing in sync from a music server. The SB3s were running Squeeze Center v7. We setup a playlist of music we both knew well then switched between monitors in pairs.