A close friend of Backhaus's, Erna Hanfstaengl was the elder sister of German-American political figure and businessman Ernst Hanfstaengl, and granddaughter of the great German photographer, Franz Hanfstaengl.  For three generations, the esteemed Hanfstaengl family were privy councilors to the Dukes of Saxe-Coburg-Gotha and well known as connoisseurs and patrons of the arts. In the years between World War I and the beginning of World War II, Erna was reported to have had romantic relations with Adolph Hitler, and her brother became an intimate follower of the Führer, later establishing a close friendship and political association that would last through the 1920s and early 1930s.  As Hitler’s fanatical theories and ideas hardened, however, he surrounded himself with rabid extremists such as Goering, Hess, and Goebbels, and Ernst became estranged from him.  According to Heinrich Himmler's personal aide and special-plenipotentiary Walter Schellenberg, Erna was also involved in a plot to overthrow Hitler and to sue for peace with the Allies.

As recounted by Ernst in his memoir, "The family enterprise my grandfather founded was, and remains to this day, one of the pioneers in the art reproduction field. My Hanfstaengl grandfather’s photographs of three German Kaisers, Moltke and Roon, Ibsen, Liszt, Wagner and Clara Schumann set the standards of their time. My father kept open house at the villa he built in the Liebigstrasse, at that time on the outskirts of Munich. Few names in the artistic world failed to grace the guest book over the years, Lilli Lehmann and Arthur Nikisch, Wilhelm Busch, Sarasate, Richard Strauss, Felix Weingartner and Wilhelm Backhaus. My parents were friends of Fritjof Nansen and Mark Twain. The atmosphere was almost ostentatiously international."