I've heard the powered Audio Engine speakers, and they sound great, for near listening low volume. If that's what you are looking for. The small speakers that Peachtree Audio uses in their demos (sorry can't remember their name) sound excellent at low volumes as well.
if you have the space and money, nothing sounds better than Quad 57's at low levels, but they take up space, and cost quite a bit for an office, but if you have a really nice office, and can afford them....