I have a 4B-ST and have used an Audio Research SP9 MkII happily for a couple of years. Though its not the end all, it was a good place to start and readily available, reliable, and affordable. The ARC offers many of the tube virtues but is still quite neutral, not euphonic. It depends a lot on your room and your speakers. (I am not familiar w/the Legacy)
Though I haven't tried one, many people advised me that the Audible Illusions 3A was a good peice to associate with this amp.
Though I haven't tried one, many people advised me that the Audible Illusions 3A was a good peice to associate with this amp.