Hi
Well I’ve purchased a pair of WE 300B’s for the Thoress amps .
Unfortunately Reinhard isn’t replying to emails so I’m seeking advice rebiasing the amps for the WE’s
Currently using Elrog ER300B’s.
Initial correspondence is it’s a resistor value change currently 51k can measure the voltage across R1+R2 if required.
Or anyone local to Southampton who can help out .
Last constructive message
Total resitance R=51.26=R1+R2=38.3K+11.96K=51.26.
A HIGHER value than with regular 300B tubes,
giving a LOWER grid bias voltage for ER300B.
In order to modify the monos we need
a composition R1+R2 with trimmable R2 with
a somewhat lower effective value than 51.26K.
It’s just figuring out the lower resistive value 
Cheers
Rob