High Quality Tube mike Preamp w 600 ohm Output

This is a complete microphone channel designed to feed a line level input on a recorder, etc. This is the same circuitry I used in my 6 input mixer I used for location master taping in the 60's. The mike pre is very hard to overload hence the absence of a resistive pad in front of the input transformer. The UTC A10 transformer can take better than +10 dbv without saturating the core. The circuit is very quiet & very clean, due to the fact that it is all class A operation, the exception being the cathode follower.

What is the reason for 100K + 68K in series in the anodes of the first stages?

Must be available resistors. 

The B+ that fed the second stage was approx. 175 vdc, I wanted lower voltage on the plate of the first stage & I forgot to show the 20mfd. filter cap on the secondary side of the 68k.