Of the available triodes, the 300B plays the most records with the greatest ease and the most refinement. It is voluptuous and elegant. Also, it is the ONLY tube I am aware of with perfect sample to sample consistency. The Western Electric 300B is always quiet and it will last forever. There is a hypnotic quality to the 300B sound that draws me into the performance like no other type of amplifier.
Operating points are next on the design agenda.
With pentodes, I like low plate voltages and high current. With triodes I like high plate voltages AND high current. 80mA standing current. I want deep class A1. Symmetrical clipping and fast graceful recovery are a combination of power tube operating point, driver stage design and power supply engineering.