Hey-Hey!!!,
I have built some linestages with cathode follower outputs. Straight triode, triode cascodes, and pentodes. I saw a description of a linestage using the type 85 tube. It was described as having a cascode 6BL7 output stage. The 85 is a high plate Z, low-ish mu triode. Seems that this output buffer would present a minimal load to its plate.
How to manage the input capacitance? Will a screen grid have more capacitance to grid than the other options? Let me gues...depends on the screen grid...:)
cheers,
Douglas