I have used the Ref 3 and now the Ref 5 which are the obvious choices for the voice matching as already said.
Beyond that I used an Ayre phono pre amp wihch I thought mated very well with various ARC pre/amp combos. I bet their preamps would work well with ARC amps. I have also always ben intrigued with VAC and would like to try some of their stuff too.
I am sure there are some more...