What are your all's feelings on this upgrade I make to the MKIII's circuit? I am getting similar number's to Shannon's Poseidon circuit with 15dB of feedback. At present I am using KT90 tubes but KT88s will yield the same numbers as well when optimized.
The mod uses all point-to-point wiring and a sheet of stainless to replace the driver board. Cermet pots are used for the phase compensation and bias pots. Photos and the schematic are below.