Greg Bahnsen's debates have been remastered with high quality audio. Unfortunately, there are very little examples of high profile presuppositionalism debates with atheists. Greg Bahnsen had at least two well known debates against Gordon Stein and Edward Tabash which previously was difficult to find and listen to. You can now listen to the remastered versions right here, brought you by the Reformed Wiki. The audio is crisp and the debates have been annotated with timestamps and helpful pop-ups to help you keep track.