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.
There are a couple of Kronzilla models.
One being entirley solid state the others being tube based (at the output).(Kronzilla HD being solid state.)
I have no idea what technology precedes the output on the tube based stuff.