The second part of my SRX Plus article is now published in the Dec 2015 issue of AudioXpress so I can complete the discussion of the shunt power supply.  The schematic is posted above.   It is almost deceptively simple, but with some neat design touches.  There are dropping resistors for the input stage tail current source, resistors to set the voltages across the output capacitor, and taps to bias the filament voltages for the input and output tubes.   The regulator tube in the July 1999 T