Let me pick your vacuum tube brains....

Haha, yes I do have it in front of a cabsim!

Just managed to find a multimeter lying around so i'll give measuring the voltages a go. If you never see me post again, you know why!!

Those models do seem to work much faster, but they introduce very strange artifacts:
400Hz test signal
Capturenewtrace.PNG

zooming on the strange areas:
Capturenewtracezoom.PNG