Blue has already turned down the possibliity of going Golden gate w/his duos because the hum is unacceptable.
Geoffrey Armstrong of Sound Galleries in Monaco runs the Big 7 on Duos without any noise issues. His amps are Audiopax and Tom Evans. He is a dealer for the other components, not for the Lampi. He also has trios with bass horns for his personal home stereo.
Superb dealer, he never oversells, and I found out only at the end of the demo that he knew the conductor, recording, etc of my classical demos. Was impressed.