Need suggestion operating point for 6H30?

[Tubenstein]

Hello!
Currently I operate the 6H30 (half the tube) in 100v @30mA. However, my friend told me 80v @40mA is the best for this tube.

Any comments?

Thanks!

 

[artosalo]

In this case what means "best"? Lowest THD? What is the load impedance in your case?

 

[Windcrest77]

This calculator has a model for that tube:

Universal loadline calculator for vacuum tubes - Vacuum Tube Amplifiers - DIY