Throughout his career, the artist was accompanied by the epithet of the “singing lion.” The description fittet his appearance, his imposing Herculean figure, his mighty head with the “Lion’s mane” - and, naturally his voice, which was of virtually incredible strength - a “lion’s voice” indeed, as Lauri-Volpi put it significantly. When his refulgent voice turned wan and pale, the reviews spoke of the “dying lion” and Ruffo himself said after he terminated his artistic career in 1936: “The lion is silent.” (Preiser)
Ruffo’s voice had something of a force of nature about it, something animalistic even. It was a singular phenomenon. His whole appearance was unique in the world of opera. Deep at heart Ruffo was, in fact, a naturalist and by no means a pure belcanto singer. His strength was the unbelievably rich volume in the highest range (which occasionally reached tenorial regions), the immediacy of tonal formation and thus an astonishing ability in “parlando” singing. This was offset by a certain huskiness in the lower range - a deficit that increased during the course of his career. As a singer Ruffo made full use of a “coloristic” palette. In his autobiography “La mia parabola” he outlined how he mixed light, dark and irridating colors.