There have been far more questions about the Tubelab SE. The parts list has been modified to reflect the changes outlined below.
If you have a Tubelab SE and it is working OK, leave it alone. If you have any instability, or have experienced blown mosfets, make these changes. If you are starting a new build, or in the process of building one, make the following changes.
Increase the grid stopper resistors on the 5842 (R31 and R32) from 1K to 4.7K ohm. These resistors should be carbon composition if at all possible. The 5842 will oscillate if given the opportunity. The higher stopper resistor value will help. If you are using a volume pot on the board, make sure that the case of the pot is grounded. The cable from the board to the input jacks should be connected to ground on the PC board, and connected to ground at the input jacks. All ground connections to the chassis should be made at the input jacks. See the wiring diagrams for the Simple SE for details. The oscillation occurs in the 100KHz range which is inaudible, but may be heard as a hum or buzz. It can also cause the output tube current to rise unexpectedly.
R14 and R25 set the operating current for the mosfets. The parts list shows a value of 20K ohms. This is good for boards that operate from 275 to 325 volts of B+. Boards that operate from 325 to 360 volts should use 30K ohms. Boards that operate from 360 volts to 400 volts should use 36K ohms. This will reduce the dissipation at higher voltages. The B+ voltage may be considerably higher than normal during the time that the tubes are warming up. This is especially true with low cost power transformers. Voltages of 450 volts and higher have been seen, which combined with high mosfet current can lead to blown mosfets on power up.
C6 should be rated for the full B+ voltage, and the expected rise on power up. This means a 350 volt cap is OK for 45 amps that run at 275 to 325 volts. A 400 volt cap should be used if your B+ is from 325 to 360 volts, and a 450 volt cap is needed for boards that run from 360 to 400 volts. It is unlikely that a 100uF cap that will fit the PC board can be found in the higher voltages. It is OK to use an 82 or 68 uF cap.