EvgenyS Это походу человек не из России 
mensur your version is seemed to be ok, except some moments:
r16-you don't need it
c8-22-100n is enough
1meg from Q2 gate to drain will be probably needed.
22mf*400v for the first tube is needed to.
ps sorry for my english 
You are right,I'm not from Russia, i'm from Serbia:-)
Now i see, only one mosfet buffer is needed, i will drop out Q2!!!
ill drop the r16(i was onlt following the marshall scheme)
C8- i know that 22nF - 100nF is enough, but again, i followed marshall...
The reason i put Q2 was to lower the impedance of the tone stack,like in Randall amps.