I have Audio Physic Libra's and am using a Music Reference RM 9 MkII, 125 WPC with 6550 tubes. This is a great match up and I am sure would work well with the Virgo's as well. I previously had a Audio Research D 70 Mk II, which did not have quiet enough power, and could not match the transparency and soundstage of the RM 9.
