If you are using single ended inputs, you only need to change the 4 tubes on the left. The 2 on the right of the main group (not the headphone ones) are used as buffers for the balanced inputs. In a recent newsletter, Cary had a picture of a modified SLP-05 they had at RMAF with 4 Black Treasures and 2 more normal tubes. People like the Black Treasures but they do not fit the holes in the top plate - you need to enlarge the holes. New Psvane tubes (CV181-T) are based on the old Treasures and are starting to become available from Grant Fidelity, at half the price of the Pope's. I thought about the Pope's but Upscale says they only sell them to people you got their pre from them. But, it sounds like your Pope's may last forever. Good luck!