I came across this unorthodox quote by Prabhupada in the Introduction of the Sri Isopanisad:
Sankaracarya is supposed to be an impersonalist who preached impersonalism, impersonal Brahman, but it is a fact that he is a covered personalist. In his commentary on the Bhagavad-Gita he wrote, " Narayana, the Supreme Personality of Godhead, is beyond this cosmic manifestation." And then again he conformed, "That Supreme Personality of Godhead, Narayana, is Krsna. He has come as the son of Devaki and Vasudeva." He particularly mentioned the names of his mother and father. So Krsna is accepted as the Supreme Personality of Godhead by all transcendentalists. There is no doubt about it (p.6).