I know I've been recommending a few folk to interview recently. But this guy has a vast knowledge about collectivism and banking, which I'm quite sure Stefan would find very engaging. Not sure if he is an anarchist or not, but he has been an outspoken critic of both collectivist and banking theories since the 1960's. A very phiolosophical gentlemen as well.
A short introduction to the man
A longer but more recent interview he had with the Tragedy and Hope channel on YouTube