• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

300B Push-Pull and PSE

mozfet,
give Lynn Olson's Amity amp a try. It is a 300B PP amp with insterstage transformer coupling.
Have not heard it, but have read nothing but enthusing raves about it.

If you plan to build it, do not use original WE 300B nor Chinese stuff. Use the Kron 300B, i listened to it. While having the juice of a 300B, this amp did not have the caramel-sauce-like sonic transparency of the original, it rather had the breathtaking real transparency and speed of a 45.