I built a linestage with a power pentode. It sounds better than any of the triode circuits I have played with. The pentode is a 6AV5GA. Screen grid is shunt regulated at 75V. The plate load is a 750R resistor. As usual there is a single input and output. B+ runs ~200V, perhaps a bit less due to rectifier drop( depending on 5R4 or 5AR4 and a few inbetween ). It idles at power-amp levels of 55 mA each.
cheers,
Douglas